Spherical cloaking with homogeneous isotropic multilayered structures.
Qiu, Cheng-Wei; Hu, Li; Xu, Xiaofei; Feng, Yijun
2009-04-01
We propose a practical realization of electromagnetic spherical cloaking by layered structure of homogeneous isotropic materials. By mimicking the classic anisotropic cloak by many alternating thin layers of isotropic dielectrics, the permittivity and permeability in each isotropic layer can be properly determined by effective medium theory in order to achieve invisibility. The model greatly facilitates modeling by Mie theory and realization by multilayer coating of dielectrics. Eigenmode analysis is also presented to provide insights of the discretization in multilayers. PMID:19518392
Making waves round a structured cloak: lattices, negative refraction and fringes.
Colquitt, D J; Jones, I S; Movchan, N V; Movchan, A B; Brun, M; McPhedran, R C
2013-09-01
Using the framework of transformation optics, this paper presents a detailed analysis of a non-singular square cloak for acoustic, out-of-plane shear elastic and electromagnetic waves. Analysis of wave propagation through the cloak is presented and accompanied by numerical illustrations. The efficacy of the regularized cloak is demonstrated and an objective numerical measure of the quality of the cloaking effect is provided. It is demonstrated that the cloaking effect persists over a wide range of frequencies. As a demonstration of the effectiveness of the regularized cloak, a Young's double slit experiment is presented. The stability of the interference pattern is examined when a cloaked and uncloaked obstacle are successively placed in front of one of the apertures. This novel link with a well-known quantum mechanical experiment provides an additional method through which the quality of cloaks may be examined. In the second half of the paper, it is shown that an approximate cloak may be constructed using a discrete lattice structure. The efficiency of the approximate lattice cloak is analysed and a series of illustrative simulations presented. It is demonstrated that effective cloaking may be obtained by using a relatively simple lattice structure, particularly, in the low-frequency regime. PMID:24062625
All-Dielectric Multilayer Cylindrical Structures for Invisibility Cloaking
Ali Mirzaei; Miroshnichenko, Andrey E.; Shadrivov, Ilya V.; Kivshar, Yuri S.
2015-01-01
We study optical response of all-dielectric multilayer structures and demonstrate that the total scattering of such structures can be suppressed leading to optimal invisibility cloaking. We use experimental material data and a genetic algorithm to reduce the total scattering by adjusting the material and thickness of various layers for several types of dielectric cores at telecommunication wavelengths. Our approach demonstrates 80-fold suppression of the total scattering cross-section by empl...
All-dielectric multilayer cylindrical structures for invisibility cloaking.
Mirzaei, Ali; Miroshnichenko, Andrey E; Shadrivov, Ilya V; Kivshar, Yuri S
2015-01-01
We study optical response of all-dielectric multilayer structures and demonstrate that the total scattering of such structures can be suppressed leading to optimal invisibility cloaking. We use experimental material data and a genetic algorithm to reduce the total scattering by adjusting the material and thickness of various layers for several types of dielectric cores at telecommunication wavelengths. Our approach demonstrates 80-fold suppression of the total scattering cross-section by employing just a few dielectric layers. PMID:25858295
Cymatics for the cloaking of flexural vibrations in a structured plate
Misseroni, D.; Colquitt, D. J.; Movchan, A. B.; Movchan, N. V.; Jones, I. S.
2016-04-01
Based on rigorous theoretical findings, we present a proof-of-concept design for a structured square cloak enclosing a void in an elastic lattice. We implement high-precision fabrication and experimental testing of an elastic invisibility cloak for flexural waves in a mechanical lattice. This is accompanied by verifications and numerical modelling performed through finite element simulations. The primary advantage of our square lattice cloak, over other designs, is the straightforward implementation and the ease of construction. The elastic lattice cloak, implemented experimentally, shows high efficiency.
Cymatics for the cloaking of flexural vibrations in a structured plate.
Misseroni, D; Colquitt, D J; Movchan, A B; Movchan, N V; Jones, I S
2016-01-01
Based on rigorous theoretical findings, we present a proof-of-concept design for a structured square cloak enclosing a void in an elastic lattice. We implement high-precision fabrication and experimental testing of an elastic invisibility cloak for flexural waves in a mechanical lattice. This is accompanied by verifications and numerical modelling performed through finite element simulations. The primary advantage of our square lattice cloak, over other designs, is the straightforward implementation and the ease of construction. The elastic lattice cloak, implemented experimentally, shows high efficiency. PMID:27068339
Homogeneous optical cloak constructed with uniform layered structures
DEFF Research Database (Denmark)
Zhang, Jingjing; Liu, Liu; Luo, Yu;
2011-01-01
The prospect of rendering objects invisible has intrigued researchers for centuries. Transformation optics based invisibility cloak design is now bringing this goal from science fictions to reality and has already been demonstrated experimentally in microwave and optical frequencies. However, the...... opportunities for using uniform layered medium to realize invisibility at any frequency ranges, where high-quality dielectrics are available. © 2011 Optical Society of America....
Ramadan, M.; Akl, W.; Elnady, T.; Elsabbagh, A.
2011-06-01
A finite-element model for three-dimensional acoustic cloaks in both cylindrical and spherical coordinates is presented. The model is developed through time-harmonic analysis to study pressure and velocity field distributions as well as the cloak's performance. The model developed accounts for the fluid-structure interaction of thin fluid-loaded shells. A plane strain model is used for the thin shell. Mechanical harmonic excitation is applied to the fluid-loaded shell to investigate the effect of mechanical oscillation of the shell on the performance of the acoustic cloak. In developing this model, a deeper insight into the acoustic cloak phenomena presented by Cummer and Shurig in 2007 is presented. Different nonlinear coordinate transformations are presented to study their effect on the acoustic cloak performance.
Ideal and nonideal electromagnetic cloaks
Zharova, Nina A.; Shadrivov, Ilya V.; Zharov, Alexander A.; Kivshar, Yuri S.
2008-01-01
We employ the analytical results for the spatial transformation of the electromagnetic fields to obtain and analyze explicit expressions for the structure of the electromagnetic fields in invisibility cloaks, beam splitters, and field concentrators. We study the efficiency of nonideal electromagnetic cloaks and discuss the effect of scattering losses on the cloak invisibility.
Making Waves Round a Structured Cloak: Lattices, Negative Refraction and Fringes
Colquitt, DJ; Movchan, NV; Brun, AB Movchan M; McPhedran, RC
2013-01-01
Using the framework of transformation optics, this paper presents a detailed analysis of a non-singular square cloak for acoustic, out-of-plane shear elastic, and electromagnetic waves. The generating map is examined in detail and linked to the material properties of the cloak. Analysis of wave propagation through the cloak is presented and accompanied by numerical illustrations. The efficacy of the regularised cloak is demonstrated and an objective numerical measure of the quality of the cloaking effect is provided. It is demonstrated that the cloaking effect persists over a wide range of frequencies. As a demonstration of the effectiveness of the regularised cloak, a Young's double slit experiment is presented. The stability of the interference pattern is examined when a cloaked and uncloaked obstacle are successively placed in front of one of the apertures. This novel link with a well-known quantum mechanical experiment provides an additional method through which the quality of cloaks may be examined. In t...
Transformation optics and invisibility cloaks
DEFF Research Database (Denmark)
Qiu, Min; Yan, Min; Yan, Wei
2008-01-01
In this paper, we briefly summarize the theory of transformation optics and introduce its application in achieving perfect invisibility cloaking. In particular, we theoretically show how the task of realizing cylindrical invisibility cloaks can be eased by using either structural approximation or...
Electromagnetic Invisibility of Elliptic Cylinder Cloaks
International Nuclear Information System (INIS)
Structures with unique electromagnetic properties are designed based on the approach of spatial coordinate transformations of Maxwell's equations. This approach is applied to scheme out invisible elliptic cylinder cloaks, which provide more feasibility for cloaking arbitrarily shaped objects. The transformation expressions for the anisotropic material parameters and the field distribution are derived. The cloaking performances of ideal and lossy elliptic cylinder cloaks are investigated by finite element simulations. It is found that the cloaking performance will degrade in the forward direction with increasing loss. (fundamental areas of phenomenology (including applications))
Chen, Huanyang; Luo, Xudong; Ma, Hongru; Chan, C. T.
2008-01-01
A kind of transformation media, which we shall call the "anti-cloak", is proposed to partially defeat the cloaking effect of the invisibility cloak. An object with an outer shell of "anti-cloak" is visible to the outside if it is coated with the invisible cloak. Fourier-Bessel analysis confirms this finding by showing that external electromagnetic wave can penetrate into the interior of the invisibility cloak with the help of the anti-cloak.
A Near Zero Refractive Index Metamaterial for Electromagnetic Invisibility Cloaking Operation
Directory of Open Access Journals (Sweden)
Sikder Sunbeam Islam
2015-07-01
Full Text Available The paper reveals the design of a unit cell of a metamaterial that shows more than 2 GHz wideband near zero refractive index (NZRI property in the C-band region of microwave spectra. The two arms of the unit cell were splitted in such a way that forms a near-pi-shape structure on epoxy resin fiber (FR-4 substrate material. The reflection and transmission characteristics of the unit cell were achieved by utilizing finite integration technique based simulation software. Measured results were presented, which complied well with simulated results. The unit cell was then applied to build a single layer rectangular-shaped cloak that operates in the C-band region where a metal cylinder was perfectly hidden electromagnetically by reducing the scattering width below zero. Moreover, the unit cell shows NZRI property there. The experimental result for the cloak operation was presented in terms of S-parameters as well. In addition, the same metamaterial shell was also adopted for designing an eye-shaped and triangular-shaped cloak structure to cloak the same object, and cloaking operation is achieved in the C-band, as well with slightly better cloaking performance. The novel design, NZRI property, and single layer C-band cloaking operation has made the design a promising one in the electromagnetic paradigm.
Invisibility cloaks for toroids.
You, Yu; Kattawar, George W; Yang, Ping
2009-04-13
The material properties of toroidal invisibility cloaks are derived based on the coordinate transformation method. The permittivity and permeability tensors for toroidal cloaks are substantially different from those for spherical cloaks, but quite similar to those for 2D cylindrical cloaks because a singularity is involved at the inner boundary in both the cases. The cloaking effect is confirmed by the electric field distribution in the vicinity of toroidal cloaks simulated from the generalized discrete-dipole approximation (DDA) method. This study extends the concept of electromagnetic cloaking of arbitrarily-shaped objects to a complex geometry. PMID:19365485
Invisibility cloak without singularity
Jiang, Wei Xiang; Cui, Tie Jun; Yang, Xin Mi; Cheng, Qiang; Liu, Ruopeng; Smith, David R
2008-01-01
An elliptical invisible cloak is proposed using a coordinate transformation in the elliptical-cylindrical coordinate system, which crushes the cloaked object to a line segment instead of a point. The elliptical cloak is reduced to a nearly-circular cloak if the elliptical focus becomes very small. The advantage of the proposed invisibility cloak is that none of the parameters is singular and the changing range of all parameters is relatively small.
Optimized cylindrical invisibility cloak with minimum layers of non-magnetic isotropic materials
International Nuclear Information System (INIS)
We present optimized design of cylindrical invisibility cloak with minimum layers of non-magnetic isotropic materials. Through an optimization procedure based on genetic algorithm, simpler cloak structure and more realizable material parameters can be achieved with better cloak performance than that of an ideal non-magnetic cloak with a reduced set of parameters. We demonstrate that a cloak shell with only five layers of two normal materials can result in an average 20 dB reduction in the scattering width for all directions when covering the inner conducting cylinder with the cloak. The optimized design can substantially simplify the realization of the invisibility cloak, especially in the optical range.
Optimized cylindrical invisibility cloak with minimum layers of non-magnetic isotropic materials
Energy Technology Data Exchange (ETDEWEB)
Yu Zhenzhong; Feng Yijun; Xu Xiaofei; Zhao Junming; Jiang Tian, E-mail: yjfeng@nju.edu.cn [Department of Electronic Engineering, School of Electronic Science and Engineering, Nanjing University, Nanjing, 210093 (China)
2011-05-11
We present optimized design of cylindrical invisibility cloak with minimum layers of non-magnetic isotropic materials. Through an optimization procedure based on genetic algorithm, simpler cloak structure and more realizable material parameters can be achieved with better cloak performance than that of an ideal non-magnetic cloak with a reduced set of parameters. We demonstrate that a cloak shell with only five layers of two normal materials can result in an average 20 dB reduction in the scattering width for all directions when covering the inner conducting cylinder with the cloak. The optimized design can substantially simplify the realization of the invisibility cloak, especially in the optical range.
Object-dependent cloaking in the first-order Born approximation
International Nuclear Information System (INIS)
We consider the cloaking of a slab object in scalar wave theory within the first-order Born approximation. We show that in the forward direction cloaking is achieved for any transversally invariant, positively refracting, and absorbing object by using a lossy, negative-index metamaterial cloak. Cloaking is perfect and occurs for incident fields having any spatial structure and bandwidth. In the backward direction cloaking is found to be possible for self-imaging fields. In both cases the refractive-index distribution and dispersive properties of the cloak slab resemble those of the object slab. The method of object-dependent cloaking with weak scatterers may find useful applications.
Experimental and computational studies of electromagnetic cloaking at microwaves
Wang, Xiaohui
An invisibility cloak is a device that can hide the target by enclosing it from the incident radiation. This intriguing device has attracted a lot of attention since it was first implemented at a microwave frequency in 2006. However, the problems of existing cloak designs prevent them from being widely applied in practice. In this dissertation, we try to remove or alleviate the three constraints for practical applications imposed by loosy cloaking media, high implementation complexity, and small size of hidden objects compared to the incident wavelength. To facilitate cloaking design and experimental characterization, several devices and relevant techniques for measuring the complex permittivity of dielectric materials at microwave frequencies are developed. In particular, a unique parallel plate waveguide chamber has been set up to automatically map the electromagnetic (EM) field distribution for wave propagation through the resonator arrays and cloaking structures. The total scattering cross section of the cloaking structures was derived based on the measured scattering field by using this apparatus. To overcome the adverse effects of lossy cloaking media, microwave cloaks composed of identical dielectric resonators made of low loss ceramic materials are designed and implemented. The effective permeability dispersion was provided by tailoring dielectric resonator filling fractions. The cloak performances had been verified by full-wave simulation of true multi-resonator structures and experimental measurements of the fabricated prototypes. With the aim to reduce the implementation complexity caused by metamaterials employment for cloaking, we proposed to design 2-D cylindrical cloaks and 3-D spherical cloaks by using multi-layer ordinary dielectric material (epsilon r>1) coating. Genetic algorithm was employed to optimize the dielectric profiles of the cloaking shells to provide the minimum scattering cross sections of the cloaked targets. The designed cloaks can
Invisibility Cloak Printed on a Photonic Chip
Feng, Zhen; Wu, Bing-Hong; Zhao, Yu-Xi; Gao, Jun; Qiao, Lu-Feng; Yang, Ai-Lin; Lin, Xiao-Feng; Jin, Xian-Min
2016-01-01
Invisibility cloak capable of hiding an object can be achieved by properly manipulating electromagnetic field. Such a remarkable ability has been shown in transformation and ray optics. Alternatively, it may be realistic to create a spatial cloak by means of confining electromagnetic field in three-dimensional arrayed waveguides and introducing appropriate collective curvature surrounding an object. We realize the artificial structure in borosilicate by femtosecond laser direct writing, where we prototype up to 5,000 waveguides to conceal millimeter-scale volume. We characterize the performance of the cloak by normalized cross correlation, tomography analysis and continuous three-dimensional viewing angle scan. Our results show invisibility cloak can be achieved in waveguide optics. Furthermore, directly printed invisibility cloak on a photonic chip may enable controllable study and novel applications in classical and quantum integrated photonics, such as invisualising a coupling or swapping operation with on-chip circuits of their own. PMID:27329510
Invisibility Cloak Printed on a Photonic Chip
Feng, Zhen; Zhao, Yu-Xi; Gao, Jun; Qiao, Lu-Feng; Yang, Ai-Lin; Lin, Xiao-Feng; Jin, Xian-Min
2016-01-01
Invisibility cloak capable of hiding an object can be achieved by properly manipulating electromagnetic field. Such a remarkable ability has been shown in transformation and ray optics. Alternatively, it may be realistic to create a spatial cloak by means of confining electromagnetic field in three-dimensional arrayed waveguides and introducing appropriate collective curvature surrounding an object. We realize the artificial structure in borosilicate by femtosecond laser direct writing, where we prototype up to 5000 waveguides to conceal millimeter-scale volume. We characterize the performance of the cloak by normalized cross correlation, tomography analysis and continuous three-dimensional viewing angle scan. Our results show invisibility cloak can be achieved in waveguide optics. Furthermore, directly printed invisibility cloak on a photonic chip may enable controllable study and novel applications in classical and quantum integrated photonics, such as invisualising a coupling or swapping operation with on-...
Invisibility Cloak Printed on a Photonic Chip.
Feng, Zhen; Wu, Bing-Hong; Zhao, Yu-Xi; Gao, Jun; Qiao, Lu-Feng; Yang, Ai-Lin; Lin, Xiao-Feng; Jin, Xian-Min
2016-01-01
Invisibility cloak capable of hiding an object can be achieved by properly manipulating electromagnetic field. Such a remarkable ability has been shown in transformation and ray optics. Alternatively, it may be realistic to create a spatial cloak by means of confining electromagnetic field in three-dimensional arrayed waveguides and introducing appropriate collective curvature surrounding an object. We realize the artificial structure in borosilicate by femtosecond laser direct writing, where we prototype up to 5,000 waveguides to conceal millimeter-scale volume. We characterize the performance of the cloak by normalized cross correlation, tomography analysis and continuous three-dimensional viewing angle scan. Our results show invisibility cloak can be achieved in waveguide optics. Furthermore, directly printed invisibility cloak on a photonic chip may enable controllable study and novel applications in classical and quantum integrated photonics, such as invisualising a coupling or swapping operation with on-chip circuits of their own. PMID:27329510
International Nuclear Information System (INIS)
In this paper, we consider invisibility cloaking via the transformation optics approach through a ‘blow-up’ construction. An ideal cloak makes use of singular cloaking material. ‘Blow-up-a-small-region’ construction and ‘truncation-of-singularity’ construction are introduced to avoid the singular structure, however, giving only near-cloaks. The study in the literature is to develop various mechanisms in order to achieve high-accuracy approximate near-cloaking devices, and also from a practical viewpoint to nearly cloak an arbitrary content. We study the problem from a different viewpoint. It is shown that for those regularized cloaking devices, the corresponding scattering wave fields due to an incident plane wave have regular patterns. The regular patterns are both a curse and a blessing. On the one hand, the regular wave pattern betrays the location of a cloaking device which is an intrinsic defect due to the ‘blow-up’ construction, and this is particularly the case for the construction by employing a high-loss layer lining. Indeed, our numerical experiments show robust reconstructions of the location, even by implementing the phaseless cross-section data. The construction by employing a high-density layer lining shows a certain promising feature. On the other hand, it is shown that one can introduce an internal point source to produce the canceling scattering pattern to achieve a near-cloak of an arbitrary order of accuracy. (paper)
Zhu, X. F.; Liang, B.; Tu, J; D. Zhang; Cheng, J C
2011-01-01
The magic "Harry Potter's cloak" has been the dream of human beings for really long time. Recently, transformation optics inspired from the advent of metamaterials offers great versatility for manipulating wave propagation at will to create amazing illusion effects. In the present work, we proposed a novel transformation recipe, in which the cloaking shell somehow behaves like a "cloaking lens", to provide almost all desired features one can expect for a real magic cloak. The most exciting fe...
Zhu, X F; Tu, J; Zhang, D; Cheng, J C
2011-01-01
The magic "Harry Potter's cloak" has been the dream of human beings for really long time. Recently, transformation optics inspired from the advent of metamaterials offers great versatility for manipulating wave propagation at will to create amazing illusion effects. In the present work, we proposed a novel transformation recipe, in which the cloaking shell somehow behaves like a "cloaking lens", to provide almost all desired features one can expect for a real magic cloak. The most exciting feature of the current recipe is that an object with arbitrary characteristics (e.g., size, shape or material properties) can be invisibilized perfectly with positive-index materials, which significantly benefits the practical realization of a broad-band cloaking device fabricated with existing materials. Moreover, the one concealed in the hidden region is able to undistortedly communicate with the surrounding world, while the lens-like cloaking shell will protect the cloaked source/sensor from being traced back by outside ...
Ultrabroadband Elastic Cloaking in Thin Plates
Farhat, Mohamed; Guenneau, Sebastien; Enoch, Stefan
2009-07-01
Control of waves with metamaterials is of great topical interest, and is fueled by rapid progress in broadband acoustic and electromagnetic cloaks. We propose a design for a cloak to control bending waves propagating in isotropic heterogeneous thin plates. This is achieved through homogenization of a multilayered concentric coating filled with piecewise constant isotropic elastic material. Significantly, our cloak displays no phase shift for both backward and forward scattering. To foster experimental efforts, we provide a simplified design of the cloak which is shown to work in a more than two-octave frequency range (30 Hz to 150 Hz) when it consists of 10 layers using only 6 different materials overall. This metamaterial should be easy to manufacture, with potential applications ranging from car industry to antiearthquake passive systems for smart buildings, depending upon the plate dimensions and wavelengths.
Natural Light Cloaking for Aquatic and Terrestrial Creatures
Chen, Hongsheng; Shen, Lian; Wang, Huaping; Zhang, Xianmin; Zheludev, Nikolay; Zhang, Baile
2013-01-01
A cloak that can hide living creatures from sight is a common feature of mythology but still remains unrealized as a practical device. To preserve the phase of wave, the previous cloaking solution proposed by Pendry \\emph{et al.} required transforming electromagnetic space around the hidden object in such a way that the rays bending around it have to travel much faster than those passing it by. The difficult phase preservation requirement is the main obstacle for building a broadband polarization insensitive cloak for large objects. Here, we suggest a simplifying version of Pendry's cloak by abolishing the requirement for phase preservation as irrelevant for observation in incoherent natural light with human eyes that are phase and polarization insensitive. This allows the cloak design to be made in large scale using commonly available materials and we successfully report cloaking living creatures, a cat and a fish, in front of human eyes.
Acoustic cloaking transformations from attainable material properties
International Nuclear Information System (INIS)
We propose a general methodology and a set of practical recipes for the construction of ultra-broadband acoustic cloaks-structures that can render themselves and a concealed object undetectable by means of acoustic scattering. The acoustic cloaks presented here are designed and function analogously to electromagnetic cloaks. However, acoustic cloaks in a fluid medium do not suffer the bandwidth limitations imposed on their electromagnetic counterparts by the finite speed of light in vacuum. In the absence of specific metamaterials having arbitrary combinations of quasi-static speed of sound and mass density, we explore the flexibility of continuum transformations that produce approximate cloaking solutions. We show that an imperfect, eikonal acoustic cloak (that is, one which is not impedance matched but is valid in the geometrical optics regime) with negligible dispersion can be designed using a simple layered geometry. Since a practical cloaking device will probably be composed of combinations of solid materials rather than fluids, it is necessary to consider the full elastic properties of such media, which support shear waves in addition to the compression waves associated with the acoustic regime. We perform a systematic theoretical and numerical investigation of the role of shear waves in elastic cloaking devices. We find that for elastic metamaterials with Poisson's ratio ν>0.49, shear waves do not alter the cloaking effect. Such metamaterials can be built from nearly incompressible rubbers (with ν∼0.499) and fluids. We expect this finding to have applications in other acoustic devices based on the form-invariance of the scalar acoustic wave equation.
Acoustic cloaking transformations from attainable material properties
Energy Technology Data Exchange (ETDEWEB)
Urzhumov, Yaroslav; Ghezzo, Fabrizia; Hunt, John; Smith, David R, E-mail: yaroslav.urzhumov@duke.ed [Center for Metamaterials and Integrated Plasmonics, Pratt School of Engineering, Duke University, Durham, NC 27708 (United States)
2010-07-15
We propose a general methodology and a set of practical recipes for the construction of ultra-broadband acoustic cloaks-structures that can render themselves and a concealed object undetectable by means of acoustic scattering. The acoustic cloaks presented here are designed and function analogously to electromagnetic cloaks. However, acoustic cloaks in a fluid medium do not suffer the bandwidth limitations imposed on their electromagnetic counterparts by the finite speed of light in vacuum. In the absence of specific metamaterials having arbitrary combinations of quasi-static speed of sound and mass density, we explore the flexibility of continuum transformations that produce approximate cloaking solutions. We show that an imperfect, eikonal acoustic cloak (that is, one which is not impedance matched but is valid in the geometrical optics regime) with negligible dispersion can be designed using a simple layered geometry. Since a practical cloaking device will probably be composed of combinations of solid materials rather than fluids, it is necessary to consider the full elastic properties of such media, which support shear waves in addition to the compression waves associated with the acoustic regime. We perform a systematic theoretical and numerical investigation of the role of shear waves in elastic cloaking devices. We find that for elastic metamaterials with Poisson's ratio {nu}>0.49, shear waves do not alter the cloaking effect. Such metamaterials can be built from nearly incompressible rubbers (with {nu}{approx}0.499) and fluids. We expect this finding to have applications in other acoustic devices based on the form-invariance of the scalar acoustic wave equation.
Cloaking an acoustic sensor with single-negative materials
Energy Technology Data Exchange (ETDEWEB)
Cai, Chen [Key Laboratory of Modern Acoustics, MOE, Department of Physics, Collaborative Innovation Center for Advanced Microstructures, Nanjing University, Nanjing 210093 (China); Zhu, Xue-Feng [Department of Physics, Huazhong University of Science and Technology, Wuhan 430074 (China); Xu, Tao [Key Laboratory of Modern Acoustics, MOE, Department of Physics, Collaborative Innovation Center for Advanced Microstructures, Nanjing University, Nanjing 210093 (China); Zou, Xin-Ye, E-mail: xyzou@nju.edu.cn [Key Laboratory of Modern Acoustics, MOE, Department of Physics, Collaborative Innovation Center for Advanced Microstructures, Nanjing University, Nanjing 210093 (China); Liang, Bin; Cheng, Jian-Chun [Key Laboratory of Modern Acoustics, MOE, Department of Physics, Collaborative Innovation Center for Advanced Microstructures, Nanjing University, Nanjing 210093 (China)
2015-07-15
In this review, a brief introduction is given to the development of acoustic superlens cloaks that allow the cloaked object to receive signals while its presence is not sensed by the surrounding, which can be regarded as “cloaking an acoustic sensor”. Remarkably, the designed cloak consists of single-negative materials with parameters independent of the background medium or the sensor system, which is proven to be a magnifying superlens. This has facilitated significantly the design and fabrication of acoustic cloaks that generally require double-negative materials with customized parameters. Such innovative design has then been simplified further as a multi-layered structure comprising of two alternately arranged complementary media with homogeneous isotropic single-negative materials. Based on this, a scattering analyses method is developed for the numerical simulation of such multi-layered cloak structures, which may serve as an efficient approach for the investigation on such devices.
Cloaking an acoustic sensor with single-negative materials
International Nuclear Information System (INIS)
In this review, a brief introduction is given to the development of acoustic superlens cloaks that allow the cloaked object to receive signals while its presence is not sensed by the surrounding, which can be regarded as “cloaking an acoustic sensor”. Remarkably, the designed cloak consists of single-negative materials with parameters independent of the background medium or the sensor system, which is proven to be a magnifying superlens. This has facilitated significantly the design and fabrication of acoustic cloaks that generally require double-negative materials with customized parameters. Such innovative design has then been simplified further as a multi-layered structure comprising of two alternately arranged complementary media with homogeneous isotropic single-negative materials. Based on this, a scattering analyses method is developed for the numerical simulation of such multi-layered cloak structures, which may serve as an efficient approach for the investigation on such devices
Electrostatic Field Invisibility Cloak
Chuwen Lan; Yuping Yang; Zhaoxin Geng; Bo Li; Ji Zhou
2015-01-01
The invisibility cloak has been drawing much attention due to its new concept for manipulating many physical fields, from oscillating wave fields (electromagnetic, acoustic and elastic) to static magnetic fields, dc electric fields, and diffusive fields. Here, an electrostatic field invisibility cloak has been theoretically investigated and experimentally demonstrated to perfectly hide two dimensional objects without disturbing their external electrostatic fields. The desired cloaking effect ...
Prolate spheroidal quantum cloak
Energy Technology Data Exchange (ETDEWEB)
Syue, Cheng-De; Lin, De-Hone, E-mail: dhlin@mail.nsysu.edu.tw [Department of Physics, National Sun Yat-sen University, Kaohsiung, Taiwan (China)
2015-04-15
To understand the propagation behavior of an oblique incident matter wave in a three-dimensional non-spherical quantum cloak, we perform the transformation design for the prolate spheroidal coordinate system and obtain a quantum cloak with an ellipsoidal shape. The mass parameters and effective potential for the creation of a perfect prolate spheroidal invisibility region are given. The analytic representations of the cloaked matter wave and probability current in the cloaking shell are presented. Special attention is paid to the discussions of the probability current in the cloaking shell for only that current can manifestly exhibit how the wave vector of the matter wave is curved, rotated, and guided in the cloaking shell to flow around the non-spherically invisible region. With the current analysis, one shows that the presented cloak can perfectly guide the matter wave in the situation of any oblique incidence. The proposed prolate spheroidal cloak for matter waves provides the first non-spherically three-dimensional setup for quantum cloaking.
Molding acoustic, electromagnetic and water waves with a single cloak
Xu, Jun
2015-06-09
We describe two experiments demonstrating that a cylindrical cloak formerly introduced for linear surface liquid waves works equally well for sound and electromagnetic waves. This structured cloak behaves like an acoustic cloak with an effective anisotropic density and an electromagnetic cloak with an effective anisotropic permittivity, respectively. Measured forward scattering for pressure and magnetic fields are in good agreement and provide first evidence of broadband cloaking. Microwave experiments and 3D electromagnetic wave simulations further confirm reduced forward and backscattering when a rectangular metallic obstacle is surrounded by the structured cloak for cloaking frequencies between 2.6 and 7.0 GHz. This suggests, as supported by 2D finite element simulations, sound waves are cloaked between 3 and 8 KHz and linear surface liquid waves between 5 and 16 Hz. Moreover, microwave experiments show the field is reduced by 10 to 30 dB inside the invisibility region, which suggests the multi-wave cloak could be used as a protection against water, sonic or microwaves. © 2015, Nature Publishing Group. All rights reserved.
Molding acoustic, electromagnetic and water waves with a single cloak.
Xu, Jun; Jiang, Xu; Fang, Nicholas; Georget, Elodie; Abdeddaim, Redha; Geffrin, Jean-Michel; Farhat, Mohamed; Sabouroux, Pierre; Enoch, Stefan; Guenneau, Sébastien
2015-01-01
We describe two experiments demonstrating that a cylindrical cloak formerly introduced for linear surface liquid waves works equally well for sound and electromagnetic waves. This structured cloak behaves like an acoustic cloak with an effective anisotropic density and an electromagnetic cloak with an effective anisotropic permittivity, respectively. Measured forward scattering for pressure and magnetic fields are in good agreement and provide first evidence of broadband cloaking. Microwave experiments and 3D electromagnetic wave simulations further confirm reduced forward and backscattering when a rectangular metallic obstacle is surrounded by the structured cloak for cloaking frequencies between 2.6 and 7.0 GHz. This suggests, as supported by 2D finite element simulations, sound waves are cloaked between 3 and 8 KHz and linear surface liquid waves between 5 and 16 Hz. Moreover, microwave experiments show the field is reduced by 10 to 30 dB inside the invisibility region, which suggests the multi-wave cloak could be used as a protection against water, sonic or microwaves. PMID:26057934
Energy Technology Data Exchange (ETDEWEB)
Zeng, Lunwu; Zhao, Yanyan; Zhao, Zhigang; Li, Hua, E-mail: 12.66@163.com
2015-04-01
We report that a bi-layer electret cylinder can cloak electrostatic field. We fabricated two hollow electret cylinders, the two hollow electret cylinders nested a bi-layer hollow electret cylinder. The direction of the polarization intensity is parallel to one of the diameters. Experimental results show that the bi-layer hollow electret cylinder can cloak electrostatic field.
Wei, Qi; Cheng, Ying; Liu, Xiaojun
2012-12-01
Based on the effective medium theory, we propose a practical implementation of a cylindrical acoustic cloak with a concentric alternating multilayered structure of homogeneous isotropic materials, which can perfectly mimic the ideal radius-dependent and anisotropic ordinary lens cloak. The proposal exhibits near-ideal cloaking performance such as low-scattering and shadow-reducing in a wide frequency range, thus it can hide an object from the detection of acoustic waves. The acoustic wave can pass through the cloaking shell with an unchanged wavefront shape, which endues the cloaked object with duplex communication ability. More simulations on the acoustic far-field scattering patterns and the total scattering cross-section are performed to investigate the layer number and the frequency dependence of the cloaking effect, and the results show that the thinner layers exhibit a better cloaking effect. The proposal may significantly facilitate the experimental demonstration of the acoustic cloak.
Designing the coordinate transformation function for non-magnetic invisibility cloaking
Energy Technology Data Exchange (ETDEWEB)
Xu Xiaofei; Feng Yijun; Zhao Lin; Jiang Tian [Department of Electronic Science and Engineering, Nanjing University, Nanjing, 210093 (China); Lu Chunhua; Xu Zhongzi [College of Materials Science and Engineering, Nanjing University of Technology, Nanjing, 210009 (China)], E-mail: yjfeng@nju.edu.cn
2008-11-07
An optical invisibility cloak based on a transformation approach has recently been proposed by a reduced set of material properties due to their easier implementation in reality and little need for an inhomogeneous permeability distribution, but the drawback of undesired scattering caused by the impedance mismatching at the outer boundary is unavoidable in such a cloak. By properly designing the coordinate transformation function to ensure impedance matching at the outer surface, we show that the performance of a nonmagnetic cylindrical cloak could be improved with minimized scattering fields. Using either a single high order power function or an optimized piecewise continuous power function, a cylindrical non-magnetic cloak has been designed with nearly perfect cloaking performance, which is better than those generated with a linear or a quadratic function. Due to the monotonicity of the designed power functions, the resulting cloak has no restriction on the size of the cloaking shell, therefore is suitable for both thick and thin cloaking structures.
Dispersive finite-difference time-domain (FDTD) analysis of the elliptic cylindrical cloak
Energy Technology Data Exchange (ETDEWEB)
Lee, Y. Y.; Ahn, D. [University of Seoul, Seoul (Korea, Republic of)
2012-05-15
A dispersive full-wave finite-difference time-domain (FDTD) model is used to calculate the performance of elliptic cylindrical cloaking devices. The permittivity and the permeability tensors for the cloaking structure are derived by using an effective medium approach in general relativity. The elliptic cylindrical invisibility devices are found to show imperfect cloaking, and the cloaking performance is found to depend on the polarization of the incident waves, the direction of the propagation of those waves, the semi-focal distances and the loss tangents of the meta-material. When the semifocal distance of the elliptic cylinder decreases, the performance of the cloaking becomes very good, with neither noticeable scatterings nor field penetrations. For a larger semi-focal distance, only the TM wave with a specific propagation direction shows good cloaking performance. Realistic cloaking materials with loss still show a cloak that is working, but attenuated back-scattering waves exist.
Broadband Acoustic Cloak for Ultrasound Waves
Zhang, Shu; Fang, Nicholas
2010-01-01
Invisibility devices based on coordinate transformation have opened up a new field of considerable interest. Such a device is proposed to render the hidden object undetectable under the flow of light or sound, by guiding and controlling the wave path through an engineered space surrounding the object. We present here the first practical realization of a low-loss and broadband acoustic cloak for underwater ultrasound. This metamaterial cloak is constructed with a network of acoustic circuit elements, namely serial inductors and shunt capacitors. Our experiment clearly shows that the acoustic cloak can effectively bend the ultrasound waves around the hidden object, with reduced scattering and shadow. Due to the non-resonant nature of the building elements, this low loss (~6dB/m) cylindrical cloak exhibits excellent invisibility over a broad frequency range from 52 to 64 kHz in the measurements. The low visibility of the cloaked object for underwater ultrasound shed a light on the fundamental understanding of ma...
Electrostatic Field Invisibility Cloak.
Lan, Chuwen; Yang, Yuping; Geng, Zhaoxin; Li, Bo; Zhou, Ji
2015-01-01
The invisibility cloak has been drawing much attention due to its new concept for manipulating many physical fields, from oscillating wave fields (electromagnetic, acoustic and elastic) to static magnetic fields, dc electric fields, and diffusive fields. Here, an electrostatic field invisibility cloak has been theoretically investigated and experimentally demonstrated to perfectly hide two dimensional objects without disturbing their external electrostatic fields. The desired cloaking effect has been achieved via both cancelling technology and transformation optics (TO). This study demonstrates a novel way for manipulating electrostatic fields, which shows promise for a wide range of potential applications. PMID:26552343
Electrostatic Field Invisibility Cloak
Lan, Chuwen; Yang, Yuping; Geng, Zhaoxin; Li, Bo; Yu, Xianglong; Zhou, Ji
2014-01-01
Invisibility cloak is drawing much attention due to its special camouflage when exposed to physical field varing from wave (electromagnetic field, acoustic field, elastic wave, etc.) to scalar field (thermal field, static magnetic field, dc electric field and mass diffusion). Here, an electrostatic field invisibility cloak has been theoretically investigated, and experimentally demonstrated for the first time to perfectly hide a certain region from sight without disturbing the external electr...
Cheng, Ying; Liu, XiaoJun
2008-11-01
It was qualitatively demonstrated through finite-element full-wave simulations that acoustic cloak can be constructed by using concentric multilayered structure with alternating homogeneous isotropic materials [Y. Cheng et al., Appl. Phys. Lett. 92, 151913 (2008)]. Here we present a sequential in-depth analysis of the proposed cloak by means of the multiple-scattering algorithms. Calculated pressure fields demonstrate that the cloak possesses low-reflection and wavefront-bending properties. The scattering patterns further characterize the directional cloaking performance in the far field, which is consistent with the pressure fields. The mechanism of the cloaking is ascribed to a specific multiple-scattering process determined by the microscopic material distribution and structural details of the cloak. We also discuss the behavior of the multilayered cloak as a function of wavelength.
Mechanical cloak design by direct lattice transformation.
Bückmann, Tiemo; Kadic, Muamer; Schittny, Robert; Wegener, Martin
2015-04-21
Spatial coordinate transformations have helped simplifying mathematical issues and solving complex boundary-value problems in physics for decades already. More recently, material-parameter transformations have also become an intuitive and powerful engineering tool for designing inhomogeneous and anisotropic material distributions that perform wanted functions, e.g., invisibility cloaking. A necessary mathematical prerequisite for this approach to work is that the underlying equations are form invariant with respect to general coordinate transformations. Unfortunately, this condition is not fulfilled in elastic-solid mechanics for materials that can be described by ordinary elasticity tensors. Here, we introduce a different and simpler approach. We directly transform the lattice points of a 2D discrete lattice composed of a single constituent material, while keeping the properties of the elements connecting the lattice points the same. After showing that the approach works in various areas, we focus on elastic-solid mechanics. As a demanding example, we cloak a void in an effective elastic material with respect to static uniaxial compression. Corresponding numerical calculations and experiments on polymer structures made by 3D printing are presented. The cloaking quality is quantified by comparing the average relative SD of the strain vectors outside of the cloaked void with respect to the homogeneous reference lattice. Theory and experiment agree and exhibit very good cloaking performance. PMID:25848021
Invisibility cloaking without superluminal propagation
Perczel, Janos; Tyc, Tomas; Leonhardt, Ulf
2011-01-01
Conventional cloaking based on Euclidean transformation optics requires that the speed of light should tend to infinity on the inner surface of the cloak. Non-Euclidean cloaking still needed media with superluminal propagation. Here we show by giving an example that this is no longer necessary.
Invisibility cloaking without superluminal propagation
Energy Technology Data Exchange (ETDEWEB)
Perczel, Janos; Leonhardt, Ulf [School of Physics and Astronomy, University of St Andrews, North Haugh, St Andrews KY16 9SS (United Kingdom); Tyc, Tomas, E-mail: jp394@st-andrews.ac.uk, E-mail: tomtyc@physics.muni.cz, E-mail: ulf@st-andrews.ac.uk [Faculty of Science, Kotlarska 2 and Faculty of Informatics, Botanicka 68a, Masaryk University, 61137 Brno (Czech Republic)
2011-08-15
Conventional cloaking based on Euclidean transformation optics requires that the speed of light should tend to infinity on the inner surface of the cloak. Non-Euclidean cloaking still needs media with superluminal propagation. Here we show by giving an example that this is no longer necessary.
International Nuclear Information System (INIS)
We present a method for designing an open acoustic cloak that can conceal a perturbation on flat ground and simultaneously meet the requirement of communication and matter interchange between the inside and the outside of the cloak. This cloak can be constructed with a multilayered structure and each layer is an isotropic and homogeneous medium. The design scheme consists of two steps: firstly, we apply a conformal coordinate transformation to obtain a quasi-perfect cloak with heterogeneous isotropic material; then, according to the profile of the material distribution, we degenerate this cloak into a multilayered-homogeneous isotropic cloak, which has two open windows with negligible disturbance on its invisibility performance. This may greatly facilitate the fabrication and enhance the applicability of such a carpet-type cloak. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)
Institute of Scientific and Technical Information of China (English)
Ren Chun-Yu; Xiang Zhi-Hai; Cen Zhang-Zhi
2011-01-01
We present a method for designing an open acoustic cloak that can conceal a perturbation on flat ground and simultaneously meet the requirement of communication and matter interchange between the inside and the outside of the cloak.This cloak can be constructed with a multilayered structure and each layer is an isotropic and homogeneous medium.The design scheme consists of two steps:firstly,we apply a conformal coordinate transformation to obtain a quasi-perfect cloak with heterogeneous isotropic material; then,according to the profile of the material distribution,we degenerate this cloak into a multilayered-homogeneous isotropic cloak,which has two open windows with negligible disturbance on its invisibility performance.This may greatly facilitate the fabrication and enhance the applicability of such a carpet-type cloak.
International Nuclear Information System (INIS)
We present the design and the experimental demonstration of an invisible cloak with irregular shape by using tensor transmission line (TL) metamaterials. The fabricated cloak consists of tensor TL unit cells exhibiting anisotropic effective material parameters, while the background medium consists of isotropic TL unit cells. The simulated and the measured field patterns around the cloak show a fairly good agreement, both demonstrate that the fabricated cloak can shield the cloaked interior area from electromagnetic fields without perturbing the external fields. The scattering of the cloaked perfect electric conductor (PEC) is minimized. Furthermore, the nonresonant property of the TL structure results in a relatively broad bandwidth of the realized cloak, which is clearly observed in our experiment. (paper)
Invisibility cloaking in weak scattering
Setälä, Tero; Hakkarainen, Timo; Ari T. Friberg; Hoenders, Bernhard J.
2010-01-01
We consider invisibility cloaking of a slab object in scalar wave theory within the first-order Born approximation. We show that in the forward direction cloaking is achieved for any object slab and incident field, whereas in the backward direction cloaking is possible at least for self-imaging fields. In both cases the scattering potential of the cloak slab depends on that of the object slab. The method of object-dependent cloaking using weak slab scatterers can be a useful addition to exist...
Cloaks with multiple invisible regions
International Nuclear Information System (INIS)
This paper proposes a general method of extending the effective invisible regions for both the shell-like interior cloak and the complementary media exterior cloak, without affecting their original cloaking regions. The proposed method is based on layered spatial mapping instead of the intact mapping. Certain interior or exterior invisible regions can be obtained by properly using a compressed or folded transformation in each space layer. Therefore, the proposal enables the as-designed cloaks to provide multiple invisible regions of different types simultaneously. Thus objects can be hidden in the interior cavity and/or in the exterior space, or even be embedded between the cloaking shells
Adaptive building skin structures
International Nuclear Information System (INIS)
The concept of adaptive and morphing structures has gained considerable attention in the recent years in many fields of engineering. In civil engineering very few practical applications are reported to date however. Non-conventional structural concepts like deployable, inflatable and morphing structures may indeed provide innovative solutions to some of the problems that the construction industry is being called to face. To give some examples, searches for low-energy consumption or even energy-harvesting green buildings are amongst such problems. This paper first presents a review of the above problems and technologies, which shows how the solution to these problems requires a multidisciplinary approach, involving the integration of architectural and engineering disciplines. The discussion continues with the presentation of a possible application of two adaptive and dynamically morphing structures which are proposed for the realization of an acoustic envelope. The core of the two applications is the use of a novel optimization process which leads the search for optimal solutions by means of an evolutionary technique while the compatibility of the resulting configurations of the adaptive envelope is ensured by the virtual force density method
Shen, Xiangying; Li, Ying; Jiang, Chaoran; Ni, Yushan; Huang, Jiping
2016-07-01
For macroscopically manipulating heat flow at will, thermal metamaterials have opened a practical way, which possesses a single function, such as either cloaking or concentrating the flow of heat even though environmental temperature varies. By developing a theory of transformation heat transfer for multiple functions, here we introduce the concept of intelligent thermal metamaterials with a dual function, which is in contrast to the existing thermal metamaterials with single functions. By assembling homogeneous isotropic materials and shape-memory alloys, we experimentally fabricate a kind of intelligent thermal metamaterials, which can automatically change from a cloak (or concentrator) to a concentrator (or cloak) when the environmental temperature changes. This work paves an efficient way for a controllable gradient of heat, and also provides guidance both for arbitrarily manipulating the flow of heat and for efficiently designing similar intelligent metamaterials in other fields.
Cloaking Effect of Superlens in Time Domain
Xiao, Meng; Dong, Jian Wen; Huang, Xueqin; Chan, Che Ting
2012-02-01
A ``perfect lens'' (ideal absorption-less slab with μ=?=-1) or ``superlens'' (a perfect lens with small absorption) can cloak a small object located in its vicinity such that no far field observer can detect the small particle, i.e., being invisible. While the problem is well understood in the steady state by solving the Maxwell equation in frequency domain, its time domain properties, such as how the cloaking effect started, remained unknown. In this paper, by using the time-dependent Green's function approach, we present a time domain study of the cloaking properties of the ``superlens'' As a current source is turned ``on,'' the system's response will be consisted of a transient response in the beginning and a steady state response in the long run. It turns out that it takes a long time (tens of thousands of cycle) for the ``perfect lens'' to build up the cloaking effect, and this required period depends on a number of factors, such as the separation between the lens and the particle, the absorption of the slab, and the dispersion of the slab. Moreover, along with many other interesting effects, we also find that, the dipole moment, on its way to be invisible, it oscillates with a decreasing amplitude.
Broadband cloaking for flexural waves
Zareei, Ahmad
2016-01-01
The governing equation for elastic waves in flexural plates is not form invariant, and hence designing a cloak for such waves faces a major challenge. Here, we present the design of a perfect broadband cloak for flexural waves through the use of a nonlinear transformation, and by matching term-by-term the original and transformed equations. For a readily achievable flexural cloak in a physical setting, we further present an approximate adoption of our perfect cloak under more restrictive physical constraints. Through direct simulation of the governing equations, we show that this cloak, as well, maintains a consistently high cloaking efficiency over a broad range of frequencies. The methodology developed here may be used for steering waves and designing cloaks in other physical systems with non form-invariant governing equations.
Electrostatic Field Invisibility Cloak
Lan, Chuwen; Zhou, Ji; Li, Bo
2014-01-01
Invisibility cloak is currently attracting much attention due to its special avenue for manipulation of physical fields,which has been demonstrated in various waves like electromagnetic field, acoustic field and elastic wave, as well as scalar fields, such as thermal field, static magnetic field and dc electric field. Here, we report on the first theoretical and experimental realization of electrostatic field invisibility cloak to shield a certain region without disturbing the external electrostatic field. Both scattering cancelling technology and transformation optics method were employed to achieve this goal.This work provides a novel method for manipulation of electrostatic field, which may find potential applications in broad areas.
Acoustic cloaking in two dimensions: a feasible approach
International Nuclear Information System (INIS)
This work proposes an acoustic structure feasible to engineer that accomplishes the requirements of acoustic cloaking design recently introduced by Cummer and Schurig (2007 New J. Phys. 9 45). The structure, which consists of a multilayered composite made of two types of isotropic acoustic metamaterials, exactly matches the conditions for the acoustic cloaking. It is also shown that the isotropic metamaterials needed can be made of sonic crystals containing two types of material cylinders, whose elastic parameters should be properly chosen in order to satisfy (in the homogenization limit) the acoustic properties under request. In contrast to electromagnetic cloaking, the structure here proposed verifies the acoustic cloaking in a wide range of wavelengths; its performance is guaranteed for any wavelength above a certain cutoff defined by the homogenization limit of the sonic crystal employed in its fabrication
Acoustic cloaking in two dimensions: a feasible approach
Torrent, Daniel; Sánchez-Dehesa, José
2008-06-01
This work proposes an acoustic structure feasible to engineer that accomplishes the requirements of acoustic cloaking design recently introduced by Cummer and Schurig (2007 New J. Phys. 9 45). The structure, which consists of a multilayered composite made of two types of isotropic acoustic metamaterials, exactly matches the conditions for the acoustic cloaking. It is also shown that the isotropic metamaterials needed can be made of sonic crystals containing two types of material cylinders, whose elastic parameters should be properly chosen in order to satisfy (in the homogenization limit) the acoustic properties under request. In contrast to electromagnetic cloaking, the structure here proposed verifies the acoustic cloaking in a wide range of wavelengths; its performance is guaranteed for any wavelength above a certain cutoff defined by the homogenization limit of the sonic crystal employed in its fabrication.
Acoustic cloaking in two dimensions: a feasible approach
Energy Technology Data Exchange (ETDEWEB)
Torrent, Daniel; Sanchez-Dehesa, Jose [Wave Phenomena Group, Department of Electronic Engineering, Polytechnic University of Valencia, C/ Camino de vera s.n., E-46022 Valencia (Spain)], E-mail: jsdehesa@upvnet.upv.es
2008-06-15
This work proposes an acoustic structure feasible to engineer that accomplishes the requirements of acoustic cloaking design recently introduced by Cummer and Schurig (2007 New J. Phys. 9 45). The structure, which consists of a multilayered composite made of two types of isotropic acoustic metamaterials, exactly matches the conditions for the acoustic cloaking. It is also shown that the isotropic metamaterials needed can be made of sonic crystals containing two types of material cylinders, whose elastic parameters should be properly chosen in order to satisfy (in the homogenization limit) the acoustic properties under request. In contrast to electromagnetic cloaking, the structure here proposed verifies the acoustic cloaking in a wide range of wavelengths; its performance is guaranteed for any wavelength above a certain cutoff defined by the homogenization limit of the sonic crystal employed in its fabrication.
Robust large dimension terahertz cloaking
Liang, Dachuan; Gu, Jianqiang; Han, Jiaguang; Yang, Yuanmu; Zhang, Shuang; Zhang, Weili
2011-01-01
Invisibility cloaking not only catches the human imagination, but also promises fascinating applications in optics and photonics. By manipulating electromagnetic waves with metamaterials, researchers have been able to realize electromagnetic cloaking in the microwave, terahertz and optical regimes. Nevertheless, the complex design and fabrication process, narrow bandwidth, and high intrinsic losses in the metamaterial-based cloaks have imposed intractable limitations on their realistic applic...
Grating-Coupled Waveguide Cloaking
Institute of Scientific and Technical Information of China (English)
WANG Jia-Fu; QU Shao-Bo; XU Zhuo; MA Hua; WANG Cong-Min; XIA Song; WANG Xin-Hua; ZHOU Hang
2012-01-01
Based on the concept of a grating-coupled waveguide (GCW),a new strategy for realizing EM cloaking is presented.Using metallic grating,incident waves are firstly coupled into the effective waveguide and then decoupled into free space behind,enabling EM waves to pass around the obstacle.Phase compensation in the waveguide keeps the wave-front shape behind the obstacle unchanged.Circular,rectangular and triangular cloaks are presented to verify the robustness of the GCW cloaking.Electric field animations and radar cross section (RCS)comparisons convincingly demonstrate the cloaking effect.
International Nuclear Information System (INIS)
We present a survey of results from various research groups under the unifying viewpoint of transformational physics, which has been recently introduced for the design of metamaterials in optics and acoustics. We illustrate the versatility of underlying geometric transforms in order to bridge wave phenomena (the different 'colours' of waves) ranging from transverse electric waves, to linear surface water waves at an air–fluid interface, to pressure waves in fluids and out-of-plane shear waves in elastic media: these waves are all governed by a second order scalar partial differential equation (PDE) invariant under geometric transform. Moreover, flexural waves propagating in thin plates represent a very peculiar situation whereby the displacement field satisfies a fourth order scalar PDE which also retains its form under geometric transform (unlike for the Navier equation in elastodynamics). Control of flexural wave trajectories is illustrated with a multilayered cloak and a carpet. Interestingly, the colours of waves can be revealed through an analysis of the band spectra of invisibility cloaks. In the context of acoustics, this suggests one can hear the shape of a drum. Alternative avenues towards cloaking based upon anomalous resonances of a negatively refracting coating (which can be seen as the result of folding the space back onto itself), and even plasmonic shells reducing the scattering cross-section of nano-objects are also addressed. (review article)
Cloaking in Heat Conduction and Light Diffusion
Schittny, Robert Johannes
2015-01-01
In free-space optics, invisibility cloaking is fundamentally limited by relativity, making passive broadband, macroscopic cloaks impossible. This thesis explores invisibility cloaking beyond ballistic optics. In the regimes of heat conduction and light diffusion, the relativity problem vanishes due to inherently slower energy transport. Macroscopic cloaks for transient heat flow and static diffusive light transport are designed, realized and experimentally characterized.
Structural rehabilitation of old buildings
Guedes, João; Varum, Humberto
2014-01-01
The present book describes the different construction systems and structural materials and solutions within the main old buildings typologies, and it analyses the particularities of each of them, including mechanical properties, structural behaviour, typical damage patterns and collapse mechanisms. Common or pioneering intervention measures to repair and/or strengthen some of these structural elements are also reviewed.
Structural building response review
International Nuclear Information System (INIS)
The integrity of a nuclear power plant during a postulated seismic event is required to protect the public against radiation. Therefore, a detailed set of seismic analyses of various structures and equipment is performed while designing a nuclear power plant. This report describes the structural response analysis method, including the structural model, soil-structure interaction as it relates to structural models, methods for seismic structural analysis, numerical integration methods, methods for non-seismic response analysis approaches for various response combinations, structural damping values, nonlinear response, uncertainties in structural properties, and structural response analysis using random properties. The report describes the state-of-the-art in these areas for nuclear power plants. It also details the past studies made at Sargent and Lundy to evaluate different alternatives and the conclusions reached for the specific purposes that those studies were intended. These results were incorporated here because they fall into the general scope of this report. The scope of the present task does not include performing new calculations
International Nuclear Information System (INIS)
Highlights: • We first propose that the cloak is composed of the bilayer of semiconductor and superconductor. • We realize the infrared broadband cloaking based on the scattering cancellation method. • The cloaking frequency can be tuned by external temperature. - Abstract: The infrared broadband tunable cloaking have been proposed and investigated with the bilayer coating materials of semiconductor (n-Ge) and high-temperature superconductor (YBa2Cu3O7), whose cloaking frequency can be controlled by external temperature. The analytical solution is derived based on the scattering cancellation cloaking technique from the Mie scattering theory, and the full-wave numerical simulation is performed by the finite element method. The calculated and simulated results have demonstrated that this invisibility cloak may reduce the total scattering cross section of the composite structure of 90% over a broad frequency band of nearly 20 THz, and the infrared cloaking frequency can be tuned by the external temperature. It can provide a feasible way to design a broadband tunable cloak
Energy Technology Data Exchange (ETDEWEB)
Wang, Xiaohua [College of Science, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China); College of Physics and Electronics, Yancheng Teachers University, Yancheng 224051 (China); Liu, Youwen, E-mail: ywliu@nuaa.edu.cn [College of Science, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China); Feng, Yuncai [College of Science, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China)
2015-06-15
Highlights: • We first propose that the cloak is composed of the bilayer of semiconductor and superconductor. • We realize the infrared broadband cloaking based on the scattering cancellation method. • The cloaking frequency can be tuned by external temperature. - Abstract: The infrared broadband tunable cloaking have been proposed and investigated with the bilayer coating materials of semiconductor (n-Ge) and high-temperature superconductor (YBa{sub 2}Cu{sub 3}O{sub 7}), whose cloaking frequency can be controlled by external temperature. The analytical solution is derived based on the scattering cancellation cloaking technique from the Mie scattering theory, and the full-wave numerical simulation is performed by the finite element method. The calculated and simulated results have demonstrated that this invisibility cloak may reduce the total scattering cross section of the composite structure of 90% over a broad frequency band of nearly 20 THz, and the infrared cloaking frequency can be tuned by the external temperature. It can provide a feasible way to design a broadband tunable cloak.
Two dimensional invisibility cloaking via transformation optics
Liu, Hongyu; Ting ZHOU
2010-01-01
We investigate two-dimensional invisibility cloaking via transformation optics approach. The cloaking media possess much more singular parameters than those having been considered for three-dimensional cloaking in literature. Finite energy solutions for these cloaking devices are studied in appropriate weighted Sobolev spaces. We derive some crucial properties of the singularly weighted Sobolev spaces. The invisibility cloaking is then justified by decoupling the underlying singular PDEs into...
EDITORIAL: Focus on Cloaking and Transformation Optics
Leonhardt, Ulf; Smith, David R.
2008-11-01
'Any sufficiently advanced technology is indistinguishable from magic', as the late Arthur C Clarke wrote. So what does it take to do magic by technology? Transformation optics has developed some tantalizing ideas and the first practical demonstrations of 'pure and applied magic'. Transformation optics gathers an unusual mix of scientists, ranging from practically-minded engineers to imaginative theoretical physicists and mathematicians or hybrids of all three. The engineers have been developing new materials with extraordinary electromagnetic properties, from materials for microwaves, to be used in radar or wireless technology, to materials for terahertz radiation and visible light. These materials typically are composites—they consist of artificial structures much smaller than the wavelength that act like man-made atoms, apart being much larger in size. The properties of these artificial atoms depend on their shapes and sizes and so they are tunable, in contrast to most real atoms or molecules. This degree of control is what makes these materials—called metamaterials—so interesting. Such new-won freedom invites the other side of the spectrum of scientists, the theorists, to dream. Just imagine there are no practical limits on electromagnetic materials—what could we do with them? One exciting application of metamaterials has been Veselago's idea of negative refraction, dating back to the 1960s. Metamaterials have breathed life into Veselago's idea, culminating in recent optical demonstrations (see for example [1,2]). Another application is cloaking, developing ideas and first experimental demonstrations for invisibility devices [3]. It turns out that both negative refraction and cloaking are examples where materials seem to transform the geometry of space. Any optical material appears to change light's perception of space, as countless optical illusions prove, but the materials of transformation optics act in more specific ways: they appear to perform
Li, Jingzhi; Liu, Hongyu; Rondi, Luca; Uhlmann, Gunther
2015-04-01
We develop a very general theory on the regularized approximate invisibility cloaking for the wave scattering governed by the Helmholtz equation in any space dimensions via the approach of transformation optics. There are four major ingredients in our proposed theory: (1) The non-singular cloaking medium is obtained by the push-forwarding construction through a transformation that blows up a subset in the virtual space, where is an asymptotic regularization parameter. will degenerate to K 0 as , and in our theory K 0 could be any convex compact set in , or any set whose boundary consists of Lipschitz hypersurfaces, or a finite combination of those sets. (2) A general lossy layer with the material parameters satisfying certain compatibility integral conditions is employed right between the cloaked and cloaking regions. (3) The contents being cloaked could also be extremely general, possibly including, at the same time, generic mediums and, sound-soft, sound-hard and impedance-type obstacles, as well as some sources or sinks. (4) In order to achieve a cloaking device of compact size, particularly for the case when is not "uniformly small", an assembly-by-components, the (ABC) geometry is developed for both the virtual and physical spaces and the blow-up construction is based on concatenating different components. Within the proposed framework, we show that the scattered wave field corresponding to a cloaking problem will converge to u 0 as , with u 0 being the scattered wave field corresponding to a sound-hard K 0. The convergence result is used to theoretically justify the approximate full and partial invisibility cloaks, depending on the geometry of K 0. On the other hand, the convergence results are conducted in a much more general setting than what is needed for the invisibility cloaking, so they are of significant mathematical interest for their own sake. As for applications, we construct three types of full and partial cloaks. Some numerical experiments are
International Nuclear Information System (INIS)
Five types of auxiliary structures are described such as were used during the construction of the Dukovany nuclear power plant, namely a portable staircase tower, a stable staircase tower, mobile tower scaffolding, mobile scaffolding on a crane track and a scaffold cradle. Basic technical data for all types of scaffolding are given. (Pu)
Extremely Thin Dielectric Metasurface for Carpet Cloaking
Hsu, LiYi; Kanté, Boubacar
2015-01-01
We demonstrate a novel and simple approach to cloaking a scatterer on a ground plane. We use an extremely thin dielectric metasurface ({\\lambda}/12) to reshape the wavefronts distorted by a scatterer in order to mimic the reflection pattern of a flat ground plane. To achieve such carpet cloaking, the reflection angle has to be equal to the incident angle everywhere on the scatterer. We use a graded metasurface and calculate the required phase gradient to achieve cloaking. Our metasurface locally provides additional phase to the wavefronts to compensate for the phase difference amongst light paths induced by the geometrical distortion. We design our metasurface in the microwave range using highly sub-wavelength dielectric resonators. We verify our design by full-wave time-domain simulations using micro-structured resonators and show that results match theory very well. This approach can be applied to hide any scatterer on a ground plane not only at microwave frequencies, but also at higher frequencies up to th...
Metasurface Cloaks for Large Cylindrical Cluster Configurations
DEFF Research Database (Denmark)
Arslanagic, Samel; Yakovlev, A.B.
2014-01-01
Here, we investigate the performance of metasurfaces used for cloaking of cluster configurations formed by different arrangements of multiple dielectric cylinders and excited by an electric line source. While a suitably designed metasurface can be used to effectively cloak isolated electrically...... small cylinders, we demonstrate that even electrically large clusters of such particles can be cloaked by covering its constituent cylinders with the metasurface cloaks. This holds for densely packed cylinders due to significantly reduced coupling by the presence of the cloaks. The results may be of...... great potential for cloaking of large objects by integrating the metasurface elements into the object....
Invisible cloak with easily-realizable metamaterials
Jiang, Wei Xiang; Yang, Xin Mi; Cheng, Qiang; Liu, Ruopeng; Smith, David R
2008-01-01
A new elliptical invisible cloak is proposed using a coordinate transformation in the elliptical-cylindrical coordinate system, which crushes the cloaked object to a line segment instead of a point. The elliptical cloak is reduced to a nearly-circular cloak if the elliptical focus becomes very small. The advantage of the proposed invisible cloak is that none of the parameters is singular and the changing range of all parameters is relatively small, and hence the cloak is much easier to realize with the metamaterial techniques currently available.
Invisibility cloaks in relativistic motion
Halimeh, Jad C; Thompson, Robert T
2015-01-01
We consider an ideal invisibility cloak which is illuminated by monochromatic light and which moves in vacuum at constant relativistic velocity with respect to the common inertial frame of light source and observer. We show that, in general, the moving cloak becomes detectable by image distortions and by generating a broad frequency spectrum of the scattered light. However, for many special combinations of incident light frequency, wave vector of light, and cloak velocity, ideal cloaking remains possible. It becomes non-reciprocal though. This means that light rays emitted by the light source arrive at the observer as though they have travelled through vacuum, but they take completely different paths after being retro-reflected at the observer position.
First experimental demonstration of an isotropic electromagnetic cloak with strict conformal mapping
Ma, Yungui; Lan, Lu; Wu, Tiantian; Jiang, Wei; Ong, C K; He, Sailing
2013-01-01
In the past years quasi-conformal mapping has been typically used to design broadband electromagnetic cloaks. However, this technique has some inherit practical limitations such as the lateral beam shift, rendering the device visible or difficult to hide a large object. In this work we circumvent these issues by using strict conformal mapping to build the first isotropic cloak. Microwave near-field measurement shows that our device (with dielectric constant larger than unity everywhere) has a very good cloaking performance and a broad frequency response. The present dielectric approach could be technically extended to the fabrication of other conformal devices at higher frequencies.
Electromagnetic cloaking of cylindrical objects by multilayer or uniform dielectric claddings
Valagiannopoulos, Constantinos A
2012-01-01
We show that dielectric or even perfectly conducting cylinders can be cloaked by a uniform or a layered dielectric cladding, without the need of any exotic or magnetic material parameters. In particular, we start by presenting a simple analytical concept that can accurately describe the cloaking effect obtained with conical silver plates in the visible spectrum. The modeled structure has been originally presented in [S. A. Tretyakov, P. Alitalo, O. Luukkonen, C. R. Simovski, Phys. Rev. Lett., vol. 103, p. 103905, 2009], where its operation as a cloak in the optical frequencies was studied only numerically. We model rigorously this configuration as a multi-layer dielectric cover surrounding the cloaked object, with excellent agreement to the simulation results of the actual device. The concept of using uniform or multilayer dielectric covers, with relative permittivities larger than unity, is then successfully extended to cloaking of impenetrable objects such as conducting cylinders.
Logarithm conformal mapping brings the cloaking effect
Lin XU; Chen, Huanyang
2014-01-01
Over the past years, invisibility cloaks have been extensively discussed since transformation optics emerges. Generally, the electromagnetic parameters of invisibility cloaks are complicated tensors, yet difficult to realize. As a special method of transformation optics, conformal mapping helps us design invisibility cloak with isotropic materials of a refractive index distribution. However, for all proposed isotropic cloaks, the refractive index range is at such a breadth that challenges cur...
Decoupling antennas in printed technology using elliptical metasurface cloaks
M. Bernety, Hossein; Yakovlev, Alexander B.
2016-01-01
In this paper, we extend the idea of reducing the electromagnetic interactions between transmitting radiators to the case of widely used planar antennas in printed technology based on the concept of mantle cloaking. Here, we show that how lightweight elliptical metasurface cloaks can be engineered to restore the intrinsic properties of printed antennas with strip inclusions. In order to present the novel approach, we consider two microstrip-fed monopole antennas resonating at slightly different frequencies cloaked by confocal elliptical metasurfaces formed by arrays of sub-wavelength periodic elements, partially embedded in the substrate. The presence of the metasurfaces leads to the drastic suppression of mutual near-field and far-field couplings between the antennas, and thus, their radiation patterns are restored as if they were isolated. Moreover, it is worth noting that this approach is not limited to printed radiators and can be applied to other planar structures as well.
Cloaked electromagnetic, acoustic, and quantum amplifiers via transformation optics.
Greenleaf, Allan; Kurylev, Yaroslav; Lassas, Matti; Leonhardt, Ulf; Uhlmann, Gunther
2012-06-26
The advent of transformation optics and metamaterials has made possible devices producing extreme effects on wave propagation. Here we describe a class of invisible reservoirs and amplifiers for waves, which we refer to as Schrödinger hats. The unifying mathematical principle on which these are based admits such devices for any time harmonic waves modeled by either the Helmholtz or Schrödinger equation, e.g., polarized waves in electromagnetism, acoustical waves and matter waves in quantum mechanics. Schrödinger hats occupy one part of a parameter-space continuum of wave-manipulating structures which also contains standard transformation optics based cloaks, resonant cloaks and cloaked sensors. Possible applications include near-field quantum microscopy. PMID:22699493
Decoupling antennas in printed technology using elliptical metasurface cloaks
Energy Technology Data Exchange (ETDEWEB)
Bernety, Hossein M., E-mail: hmehrpou@go.olemiss.edu, E-mail: yakovlev@olemiss.edu; Yakovlev, Alexander B., E-mail: hmehrpou@go.olemiss.edu, E-mail: yakovlev@olemiss.edu [Center for Applied Electromagnetic Systems Research (CAESR), Department of Electrical Engineering, University of Mississippi, University, Mississippi 38677-1848 (United States)
2016-01-07
In this paper, we extend the idea of reducing the electromagnetic interactions between transmitting radiators to the case of widely used planar antennas in printed technology based on the concept of mantle cloaking. Here, we show that how lightweight elliptical metasurface cloaks can be engineered to restore the intrinsic properties of printed antennas with strip inclusions. In order to present the novel approach, we consider two microstrip-fed monopole antennas resonating at slightly different frequencies cloaked by confocal elliptical metasurfaces formed by arrays of sub-wavelength periodic elements, partially embedded in the substrate. The presence of the metasurfaces leads to the drastic suppression of mutual near-field and far-field couplings between the antennas, and thus, their radiation patterns are restored as if they were isolated. Moreover, it is worth noting that this approach is not limited to printed radiators and can be applied to other planar structures as well.
Decoupling antennas in printed technology using elliptical metasurface cloaks
International Nuclear Information System (INIS)
In this paper, we extend the idea of reducing the electromagnetic interactions between transmitting radiators to the case of widely used planar antennas in printed technology based on the concept of mantle cloaking. Here, we show that how lightweight elliptical metasurface cloaks can be engineered to restore the intrinsic properties of printed antennas with strip inclusions. In order to present the novel approach, we consider two microstrip-fed monopole antennas resonating at slightly different frequencies cloaked by confocal elliptical metasurfaces formed by arrays of sub-wavelength periodic elements, partially embedded in the substrate. The presence of the metasurfaces leads to the drastic suppression of mutual near-field and far-field couplings between the antennas, and thus, their radiation patterns are restored as if they were isolated. Moreover, it is worth noting that this approach is not limited to printed radiators and can be applied to other planar structures as well
Finite wavelength cloaking by plasmonic resonance
Nicorovici, N-A P; Enoch, S; Tayeb, G
2008-01-01
We consider cloaking by a coated cylindrical system using plasmonic resonance, and extend previous quasistatic treatments to include the effect of finite wavelength. We show that a probe cylinder can still be cloaked at finite wavelengths, but the cloaking cylinder develops a non-zero scattering cross-section. We show that this latter effect is dominated by a monopole term in the case of an ideal (lossless) cloaking material, and by a dipole term in the case of a realistic (lossy) material. It can be reduced but not eliminated by variations of geometric or dielectric parameters of the cloaking cylinder.
Artificial Impedance Surfaces and Wire Media for Absorption and Cloaking
Padooru, Yashwanth Reddy
The main objective of this dissertation is to investigate the ability of utilizing artificial impedance surfaces and wire media for absorption and cloaking applications. The dissertation includes two parts which focus on the electromagnetic wave propagation in absorbers formed by stacked metasurfaces and structured wire media, and electromagnetic wave interaction with the cylindrical cloaking structures. In the first part, we propose a variety of physical systems that show multiband and wideband absorption properties in the microwave regime. For the multiband absorbers, we propose a simple analytical model to study the absorption properties. Further, using the same circuit model, the physical mechanisms of the observed behavior is clearly explained in terms of the open/coupled Fabry-Pérot resonators. To design wideband absorbers, we first analyze a single-layer wire medium loaded with an arbitrary material (a thin copper patch with finite bulk conductivity and a graphene patch characterized by its complex surface conductivity) at one end and a ground plane at the other. Based on the properties of the single-layer structure (which acts as a narrowband absorber), we next propose a novel multilayered mushroom structure with thin resistive patches at the wire-medium junctions for wideband absorption. To characterize the wideband properties, here, we derive new additional boundary conditions and solve the scattering problem using an analytical model developed particularly for the problem at hand. We also show a methodology to design these absorbers and explain the wideband absorption mechanisms. The second part focuses on the application of various metasurfaces for cloaking dielectric and conducting cylinders for plane-wave incidence and for line sources in close proximity. The cloaking mechanism is based on a mantle cloaking technique, wherein the scattered field produced by the object is cancelled by the cloak. The purpose of this work is to design the mantle cloaks
Detecting electromagnetic cloaks using backward-propagating waves
Salem, Mohamed
2011-08-01
A novel approach for detecting transformation-optics invisibility cloaks is proposed. The detection method takes advantage of the unusual backward-propagation characteristics of recently reported beams and pulses to induce electromagnetic scattering from the cloak. Even though waves with backward-propagating energy flux cannot penetrate the cloaking shell and interact with the cloaked objects (i.e., they do not make the cloaked object visible), they provide a mechanism for detecting the presence of cloaks. © 2011 IEEE.
Acoustic cloak/anti-cloak device with realizable passive/active metamaterials
International Nuclear Information System (INIS)
Utilizing the coordinate transformation method, together with exchange of variables between Maxwell's equations and the acoustic equations with axial-invariance in cylindrical coordinates, the acoustic parameters (anisotropic density and scalar bulk modulus) for an ideal cloak and an ideal anti-cloak are obtained. An anti-cloak allows the inside object to ‘see’ outside, but to be invisible from outside; whereas a cloak is invisible from outside, but ‘blind’ from inside. Utilizing a scattering algorithm developed in this paper, the pressure field calculation of the cloak/anti-cloak is performed and the concepts and characteristics of the acoustic cloak/anti-cloak are revisited. To be more easily achievable experimentally, a multilayered cloak/anti-cloak model with homogeneous isotropic materials is introduced, and its corresponding pressure distributions are calculated. Also, the total scattering cross-section curves for the multilayered cloak and anti-cloak over a certain frequency range are presented and compared. Finally, an active acoustic metamaterial made up of piezo-diaphragm cavity arrays is designed for the cloak/anti-cloak. Taking into account the coupling between adjacent cavity cells, a multi-control strategy for piezo-diaphragm cavity arrays is exploited, rendering possible wide ranges of effective densities and effective bulk moduli (or acoustic speeds), or even double-negative transformation medium (i.e. both density and bulk modulus parameters are negative). With such sets of active acoustic metamaterials, the cloak and anti-cloak may become both theoretically and experimentally realizable. (paper)
All-dielectric invisibility cloaks made of BaTiO3-loaded polyurethane foam
International Nuclear Information System (INIS)
Transformation optics has led the way in the development of electromagnetic invisibility cloaks from science fiction to engineering practice. Invisibility cloaks have been demonstrated over a wide range of the electromagnetic spectrum, and with a variety of different fabrication techniques. However, all previous schemes have relied on the use of metamaterials consisting of arrays of sub-wavelength inclusions. We report on the first cloaking structure made of a high-κ dielectric-loaded foam mixture. A polyurethane foam mixed with different ratios of barium titanate is used to produce the required range of permittivities, and the invisibility cloak is demonstrated to work for all incident angles over a wide range of microwave frequencies. This method will greatly facilitate the development and large-scale manufacture of a wide range of transformation optics-based structures. (paper)
All-dielectric invisibility cloaks made of BaTiO3-loaded polyurethane foam
Bao, Di; Rajab, Khalid Z.; Hao, Yang; Kallos, Efthymios; Tang, Wenxuan; Argyropoulos, Christos; Piao, Yongzhe; Yang, Shoufeng
2011-10-01
Transformation optics has led the way in the development of electromagnetic invisibility cloaks from science fiction to engineering practice. Invisibility cloaks have been demonstrated over a wide range of the electromagnetic spectrum, and with a variety of different fabrication techniques. However, all previous schemes have relied on the use of metamaterials consisting of arrays of sub-wavelength inclusions. We report on the first cloaking structure made of a high-κ dielectric-loaded foam mixture. A polyurethane foam mixed with different ratios of barium titanate is used to produce the required range of permittivities, and the invisibility cloak is demonstrated to work for all incident angles over a wide range of microwave frequencies. This method will greatly facilitate the development and large-scale manufacture of a wide range of transformation optics-based structures.
A spacetime cloak, or a history editor
International Nuclear Information System (INIS)
We introduce a new type of electromagnetic cloak, the spacetime cloak (STC), which conceals events rather than objects. Non-emitting events occurring during a restricted period are never suspected by a distant observer. The cloak works by locally manipulating the speed of light of an initially uniform light distribution, whilst the light rays themselves always follow straight paths. Any 'perfect' spacetime cloak would necessarily rely upon the technology of electromagnetic metamaterials, which has already been shown to be capable of deforming light in ways hitherto unforeseen—to produce, for example, an electromagnetic object cloak. Nevertheless, we show how it is possible to use intensity-dependent refractive indices to construct an approximate STC, an implementation that would enable the distinct signature of successful event cloaking to be observed. Potential demonstrations include systems that apparently violate quantum statistics, 'interrupt-without-interrupt' computation on convergent data channels and the illusion of a Star Trek transporter
Macroscopic invisibility cloaking of visible light
DEFF Research Database (Denmark)
Chen, Xianzhong; Luo, Y.; Zhang, Jingjing; Jiang, Kyle; Pendry, J.B.; Zhang, Shuang
2011-01-01
Invisibility cloaks, which used to be confined to the realm of fiction, have now been turned into a scientific reality thanks to the enabling theoretical tools of transformation optics and conformal mapping. Inspired by those theoretical works, the experimental realization of electromagnetic...... invisibility cloaks has been reported at various electromagnetic frequencies. All the invisibility cloaks demonstrated thus far, however, have relied on nano- or micro-fabricated artificial composite materials with spatially varying electromagnetic properties, which limit the size of the cloaked region to a...... few wavelengths. Here, we report the first realization of a macroscopic volumetric invisibility cloak constructed from natural birefringent crystals. The cloak operates at visible frequencies and is capable of hiding, for a specific light polarization, three-dimensional objects of the scale of...
Electromagnetic detection of a perfect carpet cloak.
Shi, Xihang; Gao, Fei; Lin, Xiao; Zhang, Baile
2015-01-01
It has been shown that a spherical invisibility cloak originally proposed by Pendry et al. can be electromagnetically detected by shooting a charged particle through it, whose underlying mechanism stems from the asymmetry of transformation optics applied to motions of photons and charges [PRL 103, 243901 (2009)]. However, the conceptual three-dimensional invisibility cloak that exactly follows specifications of transformation optics is formidably difficult to implement, while the simplified cylindrical cloak that has been experimentally realized is inherently visible. On the other hand, the recent carpet cloak model has acquired remarkable experimental development, including a recently demonstrated full-parameter carpet cloak without any approximation in the required constitutive parameters. In this paper, we numerically investigate the electromagnetic radiation from a charged particle passing through a perfect carpet cloak and propose an experimentally verifiable model to demonstrate symmetry breaking of transformation optics. PMID:25997798
Superluminal media formed by photonic crystals for transformation optics-based invisibility cloaks
Semouchkina, Elena; Duan, Ran; Gandji, Navid P.; Jamilan, Saeid; Semouchkin, George; Pandey, Ravi
2016-04-01
We have developed an approach to building superluminal medium for transformation optics-based devices, including invisibility cloaks, from photonic crystals. Analysis of dispersion diagrams of 2D arrays composed from dielectric rods has shown that at frequencies corresponding to the second bands formed due to bandgap opening at increase of rod permittivity, the medium formed by arrays exhibits refractive indices providing for superluminal phase velocities of propagating waves. It is further demonstrated that rod arrays with various lattice constants could be used for realizing a range of superluminal index values prescribed by transformation optics for cylindrical cloaks at arbitrary chosen operating frequency. The performed studies allowed for solving a row of problems with employment rod arrays in the cloak medium: in particular, formulating transformation optics-based prescriptions for refractive index dispersion in the cloaking shell, defining the dimensions of array fragments capable of responding similar to infinite arrays, finding optimal distribution of linear arrays sets at their coiling to form concentric material layers in the cloaking shell, and employing interaction between neighboring array sets with various lattice constants to assist the realization of prescribed index dispersion. The performance of the superluminal medium formed by rod array sets was demonstrated on an example of a cloaking shell developed for microwave frequency range. In contrast to metamaterial-based cloak media, the developed media requires neither material homogenization, nor obtaining the effective parameters with peculiar values and Lorentz’s type resonances in rods. Combination of these advantages and low losses makes photonic crystals perspective materials for invisibility cloaks operating in THz and optical ranges.
Extremely Thin Dielectric Metasurface for Carpet Cloaking
Hsu, LiYi; Lepetit, Thomas; Kanté, Boubacar
2015-01-01
We demonstrate a novel and simple approach to cloaking a scatterer on a ground plane. We use an extremely thin dielectric metasurface ({\\lambda}/12) to reshape the wavefronts distorted by a scatterer in order to mimic the reflection pattern of a flat ground plane. To achieve such carpet cloaking, the reflection angle has to be equal to the incident angle everywhere on the scatterer. We use a graded metasurface and calculate the required phase gradient to achieve cloaking. Our metasurface loca...
Macroscopic invisibility cloaking of visible light
Chen, Xianzhong; Luo, Yu; Zhang, Jingjing; Jiang, Kyle; Pendry, John B.; Zhang, Shuang
2011-01-01
Invisibility cloaks, which used to be confined to the realm of fiction, have now been turned into a scientific reality thanks to the enabling theoretical tools of transformation optics and conformal mapping. Inspired by those theoretical works, the experimental realization of electromagnetic invisibility cloaks has been reported at various electromagnetic frequencies. All the invisibility cloaks demonstrated thus far, however, have relied on nano- or micro-fabricated artificial composite mate...
An invisibility cloak using silver nanowires
Xie, Yangbo; Xu, Yadong; Zhu, Lin; Ma, Hongru; Dong, Jian-Wen
2010-01-01
In this paper, we use the parameter retrieval method together with an analytical effective medium approach to design a well-performed invisible cloak, which is based on an empirical revised version of the reduced cloak. The designed cloak can be implemented by silver nanowires with elliptical cross-sections embedded in a polymethyl methacrylate host. This cloak is numerically proved to be robust for both the inner hidden object as well as incoming detecting waves, and is much simpler thus easier to manufacture when compared with the earlier proposed one [Nat. Photon. 1, 224 (2007)].
Influence of structural design on building costs
Sattler Cantons, Fernando
2016-01-01
This paper deals with the analysis and design of two buildings for two different uses. The first one is intended for residential use, while the second is designed for office usage. These buildings will be located in the city of Trondheim, Norway. The main objective of this document is to determine how the different structural designs for the same building affect in the final costs of the structure, taking into account different materials. The materials considered during the design and anal...
Approximate quantum and acoustic cloaking
Greenleaf, Allan; Lassas, Matti; Uhlmann, Gunther
2008-01-01
At any energy E > 0, we construct a sequence of bounded potentials $V^E_{n}, n\\in\\N$, supported in an annular region $B_{out}\\setminus B_{inn}$ in three-space, which act as approximate cloaks for solutions of Schr\\"odinger's equation: For any potential $V_0\\in L^\\infty(B_{inn})$ such that E is not a Neumann eigenvalue of $-\\Delta+V_0$ in $B_{inn}$, the scattering amplitudes $a_{V_0+V_n^E}(E,\\theta,\\omega)\\to 0$ as $n\\to\\infty$. The $V^E_{n}$ thus not only form a family of approximately transparent potentials, but also function as approximate invisibility cloaks in quantum mechanics. On the other hand, for $E$ close to interior eigenvalues, resonances develop and there exist {\\it almost trapped states} concentrated in $B_{inn}$. We derive the $V_n^E$ from singular, anisotropic transformation optics-based cloaks by a de-anisotropization procedure, which we call \\emph{isotropic transformation optics}. This technique uses truncation, inverse homogenization and spectral theory to produce nonsingular, isotropic app...
Acoustic cloaking and transformation acoustics
Energy Technology Data Exchange (ETDEWEB)
Chen Huanyang [School of Physical Science and Technology, Soochow University, Suzhou, Jiangsu 215006 (China); Chan, C T, E-mail: kenyon@ust.h, E-mail: phchan@ust.h [Department of Physics and the William Mong Institute of NanoScience and Technology, The Hong Kong University of Science and Technology, Clear Water Bay (Hong Kong)
2010-03-24
In this review, we give a brief introduction to the application of the new technique of transformation acoustics, which draws on a correspondence between coordinate transformation and material properties. The technique is formulated for both acoustic waves and linear liquid surface waves. Some interesting conceptual devices can be designed for manipulating acoustic waves. For example, we can design acoustic cloaks that make an object invisible to acoustic waves, and the cloak can either encompass or lie outside the object to be concealed. Transformation acoustics, as an analog of transformation optics, can go beyond invisibility cloaking. As an illustration for manipulating linear liquid surface waves, we show that a liquid wave rotator can be designed and fabricated to rotate the wave front. The acoustic transformation media require acoustic materials which are anisotropic and inhomogeneous. Such materials are difficult to find in nature. However, composite materials with embedded sub-wavelength resonators can in principle be made and such 'acoustic metamaterials' can exhibit nearly arbitrary values of effective density and modulus tensors to satisfy the demanding material requirements in transformation acoustics. We introduce resonant sonic materials and Helmholtz resonators as examples of acoustic metamaterials that exhibit resonant behaviour in effective density and effective modulus. (topical review)
Acoustic cloaking and transformation acoustics
International Nuclear Information System (INIS)
In this review, we give a brief introduction to the application of the new technique of transformation acoustics, which draws on a correspondence between coordinate transformation and material properties. The technique is formulated for both acoustic waves and linear liquid surface waves. Some interesting conceptual devices can be designed for manipulating acoustic waves. For example, we can design acoustic cloaks that make an object invisible to acoustic waves, and the cloak can either encompass or lie outside the object to be concealed. Transformation acoustics, as an analog of transformation optics, can go beyond invisibility cloaking. As an illustration for manipulating linear liquid surface waves, we show that a liquid wave rotator can be designed and fabricated to rotate the wave front. The acoustic transformation media require acoustic materials which are anisotropic and inhomogeneous. Such materials are difficult to find in nature. However, composite materials with embedded sub-wavelength resonators can in principle be made and such 'acoustic metamaterials' can exhibit nearly arbitrary values of effective density and modulus tensors to satisfy the demanding material requirements in transformation acoustics. We introduce resonant sonic materials and Helmholtz resonators as examples of acoustic metamaterials that exhibit resonant behaviour in effective density and effective modulus. (topical review)
Topology optimized cloak for airborne sound
DEFF Research Database (Denmark)
Andkjær, Jacob Anders; Sigmund, Ole
2013-01-01
Directional acoustic cloaks that conceal an aluminum cylinder for airborne sound waves are presented in this paper. Subwavelength cylindrical aluminum inclusions in air constitute the cloak design to aid practical realizations. The positions and radii of the subwavelength cylinders are determined...
Invisibility with a tunable cloaking device
International Nuclear Information System (INIS)
Full text: In the last decades, electromagnetic cloaking devices have been extensively investigated by physicists and engineers for several reasons. A variety of approaches have been proposed for achieving invisibility based on the unusual properties of meta materials, such as the coordinate-transformation method or scattering cancellation techniques, and both of them have already been experimentally implemented successfully. However, despite all the recent improvements in cloaking techniques, it is still a challenge to make practical tunable cloaking devices. Nowadays, the designed cloaks used in the experiments are generally manufactured to work at or around a certain frequency that cannot be freely controlled after fabrication. >From the experimental point of view this is a considerable limitation to test the cloaking efficiency in different frequency ranges of operation. Hence, it would be very interesting to conceive a cloaking device whose electromagnetic properties could be controlled by an external tunable agent. Our purpose in this work is to show that a magneto-optical cloaking device under the influence of a tunable external magnetic field can be used to control the invisibility condition for a frequency range of operation. Besides, our results, which can be achieved for moderate magnetic fields and typical plasmonic materials, are shown to be robust to material losses, so that they may pave the way for developing actively tunable, versatile plasmonic cloaks. (author)
Invisibility with a tunable cloaking device
Energy Technology Data Exchange (ETDEWEB)
Kort-Kamp, W.J.M.; Rosa, F.S.S.; Pinheiro, F.A.; Farina, C. [Universidade Federal do Rio de Janeiro, RJ (Brazil)
2013-07-01
Full text: In the last decades, electromagnetic cloaking devices have been extensively investigated by physicists and engineers for several reasons. A variety of approaches have been proposed for achieving invisibility based on the unusual properties of meta materials, such as the coordinate-transformation method or scattering cancellation techniques, and both of them have already been experimentally implemented successfully. However, despite all the recent improvements in cloaking techniques, it is still a challenge to make practical tunable cloaking devices. Nowadays, the designed cloaks used in the experiments are generally manufactured to work at or around a certain frequency that cannot be freely controlled after fabrication. >From the experimental point of view this is a considerable limitation to test the cloaking efficiency in different frequency ranges of operation. Hence, it would be very interesting to conceive a cloaking device whose electromagnetic properties could be controlled by an external tunable agent. Our purpose in this work is to show that a magneto-optical cloaking device under the influence of a tunable external magnetic field can be used to control the invisibility condition for a frequency range of operation. Besides, our results, which can be achieved for moderate magnetic fields and typical plasmonic materials, are shown to be robust to material losses, so that they may pave the way for developing actively tunable, versatile plasmonic cloaks. (author)
Designing near-perfect invisibility cloaks
DEFF Research Database (Denmark)
Qiu, Min; Yan, Wei; Yan, Min
Using the theory of transformation optics, practical cylindrical invisibility cloaks can be devised to conceal objects from detection at a targeted wavelength.......Using the theory of transformation optics, practical cylindrical invisibility cloaks can be devised to conceal objects from detection at a targeted wavelength....
A simple example of temporal cloaking
Eskin, Gregory
2016-01-01
Recently the temporal cloaking was widely studied in the physical literature using the method of transformation optics (cf. M. McCall et al [9] and others). We give a simple example of temporal cloaking based on the change of coordinates and the reduction to the initialboundary value problem with additional interior conditions
Robustness of steel and composite building structures
Jaspart, Jean-Pierre; Demonceau, Jean-François; Coméliau, Ludivine
2011-01-01
Recent events such as natural catastrophes or terrorism attacks have highlighted the necessity to ensure the structural integrity of buildings under an exceptional event. According to the Eurocodes and some different other national design codes, the structural integrity of civil engineering structures should be ensured through appropriate measures but, in most cases, no precise practical guidelines on how to achieve this goal are provided. At Liège University, the robustness of building f...
Elliptic Cylindrical Invisibility Cloak, a Semianalytical Approach Using Mathieu Functions
Cojocaru, E.
2008-01-01
An elliptic cylindrical wave expansion method by using Mathieu functions is developed to obtain the scattering field for a two-dimensional elliptic cylindrical invisibility cloak. The cloak material parameters are obtained from the spatial transformation approach. A near-ideal model of the invisibility cloak is set up to solve the boundary problem at the inner boundary in the cloak shell. The proposed design provides a more practical cloak geometry when compared to previous designs of ellipti...
Detecting the existence of an invisibility cloak using temporal steering.
Chen, Shin-Liang; Chao, Ching-Shiang; Chen, Yueh-Nan
2015-01-01
An invisibility cloak provides a way to hide an object under the detection of waves. A good cloak guides the incident waves through the cloaking shell with few distortion. Even if one day a nearly perfect cloak is built, some important quantum effects, such as dephasing of the electron spin or photon polarization, may still remain. In this work, we consider the possibility that using the temporal steering of these degrees of freedom to detect the existence of an invisibility cloak. PMID:26493048
Detecting the existence of an invisibility cloak using temporal steering
Shin-Liang Chen; Ching-Shiang Chao; Yueh-Nan Chen
2015-01-01
An invisibility cloak provides a way to hide an object under the detection of waves. A good cloak guides the incident waves through the cloaking shell with few distortion. Even if one day a nearly perfect cloak is built, some important quantum effects, such as dephasing of the electron spin or photon polarization, may still remain. In this work, we consider the possibility that using the temporal steering of these degrees of freedom to detect the existence of an invisibility cloak.
Design, implementation, and extension of thermal invisibility cloaks
Youming Zhang; Hongyi Xu; Baile Zhang
2015-01-01
A thermal invisibility cloak, as inspired by optical invisibility cloaks, is a device which can steer the conductive heat flux around an isolated object without changing the ambient temperature distribution so that the object can be “invisible” to external thermal environment. While designs of thermal invisibility cloaks inherit previous theories from optical cloaks, the uniqueness of heat diffusion leads to more achievable implementations. Thermal invisibility cloaks, as well as the variatio...
Transformation thermodynamics and heat cloaking: a review
Raza, Muhammad; Liu, Yichao; Lee, El Hang; Ma, Yungui
2016-04-01
This article is a review of the advances and progresses in the field of heat cloaking which is being realized using metamaterials. Heat cloaking has been a particularly important subject of study due to its potential multidimensional applications. The process which manipulates the heat flux in such a way that it can neither enter into the cloaked region nor be distorted outside is called thermal cloaking. Transformation optics has made the hitherto inconceivable advancements in the field of thermodynamics possible with the remarkable assistance of metamaterials. In this article we present a review of the work done in the field of heat cloaking, its progress and outlook. We discuss the theoretical and experimental studies, models, design managements, implementations and behaviors of thermal invisibility cloaking and related devices. This review is intended to help further develop practical and applicable concepts, examine fabrication techniques for a variety of different invisibility cloaking devices and systems, and to pave a way for the new avenues leading to new future technologies.
Enhancement of non-resonant dielectric cloaks using anisotropic composites
Takezawa, Akihiro
2014-01-01
The effectiveness of homogenized anisotropic materials in non-resonant dielectric multilayer cloaking is studied. Because existing multilayer cloaking by isotropic materials can be regarded as homogenous anisotropic cloaking from a macroscopic view, they can be efficiently designed by handling the physical properties of anisotropic materials directly. Anisotropic properties can be realized in two-phase composites if the physical properties of the material are within appropriate bounds. The optimized anisotropic physical properties are identified by a numerical optimization technique based on a full-wave simulation using the finite element method. The cloaking performance measured by the total scattering width is improved by about 10% compared with existing multilayer cloaking by isotropic materials in eight-layer cylindrical cloaking materials. The same performance with eight-layer cloaking by isotropic materials is achieved by three-layer cloaking using anisotropic materials. Cloaking with a about 50% reduct...
On Near-cloak in Acoustic Scattering
Liu, Hongyu
2012-01-01
We consider invisibility cloaking of active/radiating objects in acoustic scattering via the approach of transformation optics. A general lossy layer is incorporated into the construction of the near-cloaking devices. We derive very accurate estimates of the scattering amplitude in terms of the regularization parameter and the material parameters of the lossy layer in different settings. Our results on the one hand show how to cloak active contents more efficiently, and on the other hand indicate the optimal choice of choosing the lossy layer.
Theory of diffusive light scattering cancellation cloaking
Farhat, Mohamed; Guenneau, Sebastien; Bagci, Hakan; Salama, Khaled Nabil; Alu, Andrea
2016-01-01
We report on a new concept of cloaking objects in diffusive light regime using the paradigm of the scattering cancellation and mantle cloaking techniques. We show numerically that an object can be made completely invisible to diffusive photon density waves, by tailoring the diffusivity constant of the spherical shell enclosing the object. This means that photons' flow outside the object and the cloak made of these spherical shells behaves as if the object were not present. Diffusive light invisibility may open new vistas in hiding hot spots in infrared thermography or tissue imaging.
International Nuclear Information System (INIS)
The invention of the three-dimensional woodpile photonic crystal by Costas M. Soukoulis and coworkers in 1994 has stimulated much further research - excellent research stimulates further research. Here, we report on using spatially inhomogeneous polymer woodpile structures in the long-wavelength limit as artificial graded-index structures. After briefly reviewing previous work on carpet invisibility cloaks designed by transformation optics, we present new experiments for various focus planes of the inspecting microscope as well as for different inspection angles in three-dimensional space. Numerical ray-tracing modeling is also provided. These data confirm our previous assessment that three-dimensional cloaking is quite robust for these structures.
Energy Technology Data Exchange (ETDEWEB)
Ergin, Tolga, E-mail: tolga.ergin@kit.edu [Institute of Applied Physics, Institute of Nanotechnology, and DFG-Center for Functional Nanostructures (CFN), Karlsruhe Institute of Technology (KIT), 76128 Karlsruhe (Germany); Fischer, Joachim; Wegener, Martin [Institute of Applied Physics, Institute of Nanotechnology, and DFG-Center for Functional Nanostructures (CFN), Karlsruhe Institute of Technology (KIT), 76128 Karlsruhe (Germany)
2012-10-15
The invention of the three-dimensional woodpile photonic crystal by Costas M. Soukoulis and coworkers in 1994 has stimulated much further research - excellent research stimulates further research. Here, we report on using spatially inhomogeneous polymer woodpile structures in the long-wavelength limit as artificial graded-index structures. After briefly reviewing previous work on carpet invisibility cloaks designed by transformation optics, we present new experiments for various focus planes of the inspecting microscope as well as for different inspection angles in three-dimensional space. Numerical ray-tracing modeling is also provided. These data confirm our previous assessment that three-dimensional cloaking is quite robust for these structures.
A Cloaking Device for Transiting Planets
Kipping, David M
2016-01-01
The transit method is presently the most successful planet discovery and characterization tool at our disposal. Other advanced civilizations would surely be aware of this technique and appreciate that their home planet's existence and habitability is essentially broadcast to all stars lying along their ecliptic plane. We suggest that advanced civilizations could cloak their presence, or deliberately broadcast it, through controlled laser emission. Such emission could distort the apparent shape of their transit light curves with relatively little energy, due to the collimated beam and relatively infrequent nature of transits. We estimate that humanity could cloak the Earth from Kepler-like broadband surveys using an optical monochromatic laser array emitting a peak power of about 30 MW for roughly 10 hours per year. A chromatic cloak, effective at all wavelengths, is more challenging requiring a large array of tunable lasers with a total power of approximately 250 MW. Alternatively, a civilization could cloak ...
Macroscopic Invisible Cloak for Visible Light
Zhang, Baile; Liu, Xiaogang; Barbastathis, George
2011-01-01
Invisibility cloaks, a subject that usually occurs in science fiction and myths, have attracted wide interest recently because of their possible realization. The biggest challenge to true invisibility is known to be the cloaking of a macroscopic object in the broad range of wavelengths visible to the human eye. Here we experimentally solve this problem by incorporating the principle of transformation optics into a conventional optical lens fabrication with low-cost materials and simple manufacturing techniques. A transparent cloak made of two pieces of calcite is created. This cloak is able to conceal a macroscopic object with a maximum height of 2 mm, larger than 3500 free-space-wavelength, inside a transparent liquid environment. Its working bandwidth encompassing red, green and blue light is also demonstrated.
Permittivity and permeability tensors for cloaking applications
Choudhury, Balamati; Jha, Rakesh Mohan
2016-01-01
This book is focused on derivations of analytical expressions for stealth and cloaking applications. An optimal version of electromagnetic (EM) stealth is the design of invisibility cloak of arbitrary shapes in which the EM waves can be controlled within the cloaking shell by introducing a prescribed spatial variation in the constitutive parameters. The promising challenge in design of invisibility cloaks lies in the determination of permittivity and permeability tensors for all the layers. This book provides the detailed derivation of analytical expressions of the permittivity and permeability tensors for various quadric surfaces within the eleven Eisenhart co-ordinate systems. These include the cylinders and the surfaces of revolutions. The analytical modeling and spatial metric for each of these surfaces are provided along with their tensors. This mathematical formulation will help the EM designers to analyze and design of various quadratics and their hybrids, which can eventually lead to design of cloakin...
Transformation elastodynamics and active exterior acoustic cloaking
Vasquez, Fernando Guevara; Onofrei, Daniel; Seppecher, Pierre
2011-01-01
This chapter consists of three parts. In the first part we recall the elastodynamic equations under coordinate transformations. The idea is to use coordinate transformations to manipulate waves propagating in an elastic material. Then we study the effect of transformations on a mass-spring network model. The transformed networks can be realized with "torque springs", which are introduced here and are springs with a force proportional to the displacement in a direction other than the direction of the spring terminals. Possible homogenizations of the transformed networks are presented, with potential applications to cloaking. In the second and third parts we present cloaking methods that are based on cancelling an incident field using active devices which are exterior to the cloaked region and that do not generate significant fields far away from the devices. In the second part, the exterior cloaking problem for the Laplace equation is reformulated as the problem of polynomial approximation of analytic function...
Macroscopic Invisibility Cloak for Visible Light
Zhang, Baile; Luo, Yuan; Liu, Xiaogang; Barbastathis, George
2010-01-01
Invisibility cloaks, a subject that usually occurs in science fiction and myths, have attracted wide interest recently because of their possible realization. The biggest challenge to true invisibility is known to be the cloaking of a macroscopic object in the broad range of wavelengths visible to the human eye. Here we experimentally solve this problem by incorporating the principle of transformation optics into a conventional optical lens fabrication with low-cost materials and simple manufa...
Enhancement of non-resonant dielectric cloaks using anisotropic composites
International Nuclear Information System (INIS)
Cloaking techniques conceal objects by controlling the flow of electromagnetic waves to minimize scattering. Herein, the effectiveness of homogenized anisotropic materials in non-resonant dielectric multilayer cloaking is studied. Because existing multilayer cloaking by isotropic materials can be regarded as homogenous anisotropic cloaking from a macroscopic view, anisotropic materials can be efficiently designed through optimization of their physical properties. Anisotropic properties can be realized in two-phase composites if the physical properties of the material are within appropriate bounds. The optimized anisotropic physical properties are identified by a numerical optimization technique based on a full-wave simulation using the finite element method. The cloaking performance measured by the total scattering width is improved by about 2.8% and 25% in eight- and three-layer cylindrical cloaking materials, respectively, compared with multilayer cloaking by isotropic materials. In all cloaking examples, the optimized microstructures of the two-phase composites are identified as the simple lamination of two materials, which maximizes the anisotropy. The same performance as published for eight-layer cloaking by isotropic materials is achieved by three-layer cloaking using the anisotropic material. Cloaking with an approximately 50% reduction of total scattering width is achieved even in an octagonal object. Since the cloaking effect can be realized using just a few layers of the laminated anisotropic dielectric composite, this may have an advantage in the mass production of cloaking devices
Enhancement of non-resonant dielectric cloaks using anisotropic composites
Energy Technology Data Exchange (ETDEWEB)
Takezawa, Akihiro, E-mail: akihiro@hiroshima-u.ac.jp; Kitamura, Mitsuru [Division of Mechanical Systems and Applied Mechanics, Institute of Engineering, Hiroshima University, 1-4-1 Kagamiyama, Higashi-Hiroshima, Hiroshima (Japan)
2014-01-15
Cloaking techniques conceal objects by controlling the flow of electromagnetic waves to minimize scattering. Herein, the effectiveness of homogenized anisotropic materials in non-resonant dielectric multilayer cloaking is studied. Because existing multilayer cloaking by isotropic materials can be regarded as homogenous anisotropic cloaking from a macroscopic view, anisotropic materials can be efficiently designed through optimization of their physical properties. Anisotropic properties can be realized in two-phase composites if the physical properties of the material are within appropriate bounds. The optimized anisotropic physical properties are identified by a numerical optimization technique based on a full-wave simulation using the finite element method. The cloaking performance measured by the total scattering width is improved by about 2.8% and 25% in eight- and three-layer cylindrical cloaking materials, respectively, compared with multilayer cloaking by isotropic materials. In all cloaking examples, the optimized microstructures of the two-phase composites are identified as the simple lamination of two materials, which maximizes the anisotropy. The same performance as published for eight-layer cloaking by isotropic materials is achieved by three-layer cloaking using the anisotropic material. Cloaking with an approximately 50% reduction of total scattering width is achieved even in an octagonal object. Since the cloaking effect can be realized using just a few layers of the laminated anisotropic dielectric composite, this may have an advantage in the mass production of cloaking devices.
Enhancement of non-resonant dielectric cloaks using anisotropic composites
Directory of Open Access Journals (Sweden)
Akihiro Takezawa
2014-01-01
Full Text Available Cloaking techniques conceal objects by controlling the flow of electromagnetic waves to minimize scattering. Herein, the effectiveness of homogenized anisotropic materials in non-resonant dielectric multilayer cloaking is studied. Because existing multilayer cloaking by isotropic materials can be regarded as homogenous anisotropic cloaking from a macroscopic view, anisotropic materials can be efficiently designed through optimization of their physical properties. Anisotropic properties can be realized in two-phase composites if the physical properties of the material are within appropriate bounds. The optimized anisotropic physical properties are identified by a numerical optimization technique based on a full-wave simulation using the finite element method. The cloaking performance measured by the total scattering width is improved by about 2.8% and 25% in eight- and three-layer cylindrical cloaking materials, respectively, compared with multilayer cloaking by isotropic materials. In all cloaking examples, the optimized microstructures of the two-phase composites are identified as the simple lamination of two materials, which maximizes the anisotropy. The same performance as published for eight-layer cloaking by isotropic materials is achieved by three-layer cloaking using the anisotropic material. Cloaking with an approximately 50% reduction of total scattering width is achieved even in an octagonal object. Since the cloaking effect can be realized using just a few layers of the laminated anisotropic dielectric composite, this may have an advantage in the mass production of cloaking devices.
Enhancement of non-resonant dielectric cloaks using anisotropic composites
Takezawa, Akihiro; Kitamura, Mitsuru
2014-01-01
Cloaking techniques conceal objects by controlling the flow of electromagnetic waves to minimize scattering. Herein, the effectiveness of homogenized anisotropic materials in non-resonant dielectric multilayer cloaking is studied. Because existing multilayer cloaking by isotropic materials can be regarded as homogenous anisotropic cloaking from a macroscopic view, anisotropic materials can be efficiently designed through optimization of their physical properties. Anisotropic properties can be realized in two-phase composites if the physical properties of the material are within appropriate bounds. The optimized anisotropic physical properties are identified by a numerical optimization technique based on a full-wave simulation using the finite element method. The cloaking performance measured by the total scattering width is improved by about 2.8% and 25% in eight- and three-layer cylindrical cloaking materials, respectively, compared with multilayer cloaking by isotropic materials. In all cloaking examples, the optimized microstructures of the two-phase composites are identified as the simple lamination of two materials, which maximizes the anisotropy. The same performance as published for eight-layer cloaking by isotropic materials is achieved by three-layer cloaking using the anisotropic material. Cloaking with an approximately 50% reduction of total scattering width is achieved even in an octagonal object. Since the cloaking effect can be realized using just a few layers of the laminated anisotropic dielectric composite, this may have an advantage in the mass production of cloaking devices.
Acoustic cloaking using layered pentamode materials.
Scandrett, Clyde L; Boisvert, Jeffrey E; Howarth, Thomas R
2010-05-01
While receiving less attention in the literature than electromagnetic cloaking, theoretical efforts to define and create acoustic cloaks based upon mimicking coordinate transformations through use of metamaterials is of interest. The present work extends recent analysis of Norris [Proc. R. Soc. London, Ser. A 464, 2411-2434 (2008)] by considering a range of cloaks, from those comprised of fluid layers which are isotropic in bulk moduli with anisotropic density to those having anisotropic bulk moduli and isotropic density. In all but pure inertial varieties, fluid layers comprising the cloaks are pentamode materials governed by a special scalar acoustic equation for pseudopressure derived by Norris. In most cases presented, material properties of the fluid/pentamode layers are based upon target values specified by continuously varying properties resulting from theoretical coordinate transformations geared to minimize scattered pressure limited by realistic goals. The present work analyzes such cloaks for the specific case of plane wave scattering from an acoustically hard sphere. An initial exploration of the parameter space defining such cloaks (for example, material properties of its constituent layers, and operating frequency) is undertaken with a view toward "optimal" design. PMID:21117736
Elliptical metasurfaces for cloaking and antenna applications at microwave and terahertz frequencies
Mehrpourbernety, Hossein
One of the interesting applications of metamaterials is the phenomenon of electromagnetic invisibility and cloaking, which implies the suppression of bistatic scattering width of a given object, independent of incident and observation angles. In this regard, diverse techniques have been proposed to analyze and design electromagnetic cloak structures, including transformation optics, anomalous resonance methods, transmission-line networks, and plasmonic cloaking, among others. A common drawback of all these methods is that they rely on bulk materials, which are difficult to realize in practice. To overcome this issue, the mantle cloaking method has been proposed, which utilizes an ultrathin metasurface that provides anti-phase surface currents to reduce the scattering dominant mode of a given object. Recently, an analytical model has been proposed to cloak dielectric and conducting cylindrical objects realized with printed and slotted arrays at microwave frequencies. At low-terahertz (THz) frequencies, one of the promising materials to realize the required metasurface is graphene. In this regard, a graphene monolayer, characterized by inductive reactance, has been proposed to cloak dielectric planar and cylindrical objects. Then, it has been shown that a metasurface made of graphene nanopatches owns dual capacitive/inductive inductance and can be used to cloak both dielectric and conducting cylindrical objects at low-THz frequencies. So far, planar and cylindrical dielectric and conducting structures have been studied. In our study, we have extended the concept and presented an accurate analytical approach to investigate the cloaking of two-dimensional (2-D) elliptical objects including infinite dielectric elliptical cylinders using graphene monolayer; metallic elliptical cylinders, and also, as a special case, 2-D metallic strips using a nanostructured graphene patch array at low-THz frequencies. We have also obtained the results for cloaking of ellipses at
An ultrathin invisibility skin cloak for visible light.
Ni, Xingjie; Wong, Zi Jing; Mrejen, Michael; Wang, Yuan; Zhang, Xiang
2015-09-18
Metamaterial-based optical cloaks have thus far used volumetric distribution of the material properties to gradually bend light and thereby obscure the cloaked region. Hence, they are bulky and hard to scale up and, more critically, typical carpet cloaks introduce unnecessary phase shifts in the reflected light, making the cloaks detectable. Here, we demonstrate experimentally an ultrathin invisibility skin cloak wrapped over an object. This skin cloak conceals a three-dimensional arbitrarily shaped object by complete restoration of the phase of the reflected light at 730-nanometer wavelength. The skin cloak comprises a metasurface with distributed phase shifts rerouting light and rendering the object invisible. In contrast to bulky cloaks with volumetric index variation, our device is only 80 nanometer (about one-ninth of the wavelength) thick and potentially scalable for hiding macroscopic objects. PMID:26383946
50 CFR 260.99 - Buildings and structures.
2010-10-01
... 50 Wildlife and Fisheries 7 2010-10-01 2010-10-01 false Buildings and structures. 260.99 Section... Contract Basis 1 § 260.99 Buildings and structures. The buildings and structures shall be properly..., ceilings, partitions, posts, doors, and other parts of all buildings and structures shall be of...
Photorealistic rendering of unidirectional free-space invisibility cloaks
Halimeh, J.C.; Wegener, M.
2013-01-01
Carpet or ground-plane invisibility cloaks hide an object in reflection and inhibit transmission by construction. This concept has significantly reduced the otherwise demanding material requirements and has hence enabled various experimental demonstrations. In contrast, free-space invisibility cloaks should work in both reflection and transmission. The fabrication of omnidirectional three-dimensional free-space cloaks still poses significant challenges. Recently, the idea of the carpet cloak ...
On Directionality of Phrase Structure Building
Chesi, Cristiano
2015-01-01
Minimalism in grammatical theorizing (Chomsky in "The minimalist program." MIT Press, Cambridge, 1995) led to simpler linguistic devices and a better focalization of the core properties of the structure building engine: a lexicon and a free (recursive) phrase formation operation, dubbed Merge, are the basic components that serve in…
Towards all-dielectric, polarization-independent optical cloaks
DEFF Research Database (Denmark)
Andkjær, Jacob Anders; Mortensen, N. Asger; Sigmund, Ole
2012-01-01
Fully enclosing, all-dielectric cloaks working for both E-z and H-z polarizations simultaneously are presented in this letter. The cloaks are effective for two antiparallel angles of incidence, and the layout of standard dielectric material in the cloak is determined by topology optimization. Sca...
On the sensitivity of the 2D electromagnetic invisibility cloak
International Nuclear Information System (INIS)
A computational study of the sensitivity of the two dimensional (2D) electromagnetic invisibility cloaks is performed with the finite element method. A circular metallic object is covered with the cloak and the effects of absorption, gain and disorder are examined. Also the effect of covering the cloak with a thin dielectric layer is studied.
Cloak based on the angle dependent constitutive parameters tensors.
Gurvitz, Egor; Andronaki, Semen; Vozianova, Anna; Khodzitsky, Mikhail
2015-10-01
The transformation optics cloak was proposed for the medium with the angle dependent tensors of permittivity and permeability consisted of the right-handed and left-handed metamaterial media. The cloaking effect was numerically simulated using finite element method in the terahertz frequency range for different wave sources. The impact of cloaking medium thickness on the invisibility effect was demonstrated. PMID:26480088
On the sensitivity of the 2D electromagnetic invisibility cloak
Energy Technology Data Exchange (ETDEWEB)
Kaproulias, S. [Department of Physics, University of Patras, 26504 Patras (Greece); Sigalas, M.M., E-mail: sigalas@upatras.gr [Department of Materials Science, University of Patras, 26504 Patras (Greece)
2012-10-15
A computational study of the sensitivity of the two dimensional (2D) electromagnetic invisibility cloaks is performed with the finite element method. A circular metallic object is covered with the cloak and the effects of absorption, gain and disorder are examined. Also the effect of covering the cloak with a thin dielectric layer is studied.
Structural assessment of a modern heritage building
S. Sorace; Terenzi, G
2013-01-01
A structural assessment study on " Palazzo del Lavoro" in Turin, a masterpiece by Pier Luigi Nervi, was carried out within a National Research Project dedicated to the analysis of modern heritage architecture in Italy. Based on the original design documentation collected through records, a complete finite element model of the building was generated. The study included detailed models of the main structural members, represented by monumental reinforced concrete columns, a mushroom-type steel r...
Broadband surface-wave transformation cloak.
Xu, Su; Xu, Hongyi; Gao, Hanhong; Jiang, Yuyu; Yu, Faxin; Joannopoulos, John D; Soljačić, Marin; Chen, Hongsheng; Sun, Handong; Zhang, Baile
2015-06-23
Guiding surface electromagnetic waves around disorder without disturbing the wave amplitude or phase is in great demand for modern photonic and plasmonic devices, but is fundamentally difficult to realize because light momentum must be conserved in a scattering event. A partial realization has been achieved by exploiting topological electromagnetic surface states, but this approach is limited to narrow-band light transmission and subject to phase disturbances in the presence of disorder. Recent advances in transformation optics apply principles of general relativity to curve the space for light, allowing one to match the momentum and phase of light around any disorder as if that disorder were not there. This feature has been exploited in the development of invisibility cloaks. An ideal invisibility cloak, however, would require the phase velocity of light being guided around the cloaked object to exceed the vacuum speed of light--a feat potentially achievable only over an extremely narrow band. In this work, we theoretically and experimentally show that the bottlenecks encountered in previous studies can be overcome. We introduce a class of cloaks capable of remarkable broadband surface electromagnetic waves guidance around ultrasharp corners and bumps with no perceptible changes in amplitude and phase. These cloaks consist of specifically designed nonmagnetic metamaterials and achieve nearly ideal transmission efficiency over a broadband frequency range from 0(+) to 6 GHz. This work provides strong support for the application of transformation optics to plasmonic circuits and could pave the way toward high-performance, large-scale integrated photonic circuits. PMID:26056299
Acoustic cloaking by a superlens with single-negative materials.
Zhu, Xuefeng; Liang, Bin; Kan, Weiwei; Zou, Xinye; Cheng, Jianchun
2011-01-01
We propose a specific transformation in cloaking to make an acoustic sensor undetectable, in which the cloaking shell consists of complementary media with single-negative acoustic parameters instead of double-negative ones, and is proved to be a magnifying superlens. Moreover, the acoustical parameters of the cloak are completely independent of those of the host material as well as the cloaked object. This may significantly facilitate the experimental realization of acoustic cloaks and is of fundamental importance in a wide range of acoustics, optics, and engineering applications. PMID:21231745
Invisibility cloaks for irregular particles using coordinate transformations.
You, Yu; Kattawar, George W; Zhai, Peng-Wang; Yang, Ping
2008-04-28
Invisibility cloaks for ellipsoids, rounded cuboids and rounded cylinders have been studied on the basis of the coordinate transformation approach. The resultant material property tensors for irregular cloaks are more complicated in comparison with those for the spherical invisibility cloak. A generalized Discrete Dipole Approximation (DDA) formalism has been used to simulate the scattered field distribution in the vicinity of the aforementioned irregular cloaks illuminated by an incident plane wave. Simulated scattering efficiencies are on the order of 10(-5), and the simulated electric-field distribution outside of a cloak is the same as that of the incident radiation. PMID:18545315
Physical Bounds on Absorption and Scattering for Cloaked Sensors
Fleury, Romain; Alu, Andrea
2013-01-01
We derive and discuss general physical bounds on the electromagnetic scattering and absorption of passive structures. Our theory, based on passivity and power conservation, quantifies the minimum and maximum allowed scattering for an object that absorbs a given level of power. We show that there is a fundamental trade-off between absorption and overall scattering suppression for each scattering harmonic, providing a tool to quantify the performance of furtive sensors, regardless of the applied principle for scattering suppression. We illustrate these fundamental limitations with examples of light scattering from absorbing plasmonic nanoparticles and loaded dipole antennas, envisioning applications to the design of cloaked sensors and absorbers with maximized absorption efficiency.
STRUCTURAL VULNERABILITY ASSESSMENT OF MASONRY BUILDINGS IN TURKEY
Korkmaz, Kasım Armagan; CARHOGLU, Asuman Isıl
2011-01-01
Turkey is located in an active seismic zone. Mid to high rise R/C building and low rise masonry buildings are very common construction type in Turkey. In recent earthquakes, lots of existing buildings got damage including masonry buildings. Masonry building history in Turkey goes long years back. For sure, it is an important structure type for Turkey. Therefore, earthquake behavior and structural vulnerability of masonry buildings are crucial issues for Turkey as a earthquake prone country. I...
The effect of electrostatic shielding using invisibility cloak
Zhang, Ruo-Yang; Ge, Mo-Lin
2011-01-01
The effect of electrostatic shielding for a spherical invisibility cloak with arbitrary charges inside is investigated. Our result reveals that the charge inside the cloak is a crucial factor to determine the detection. When charged bodies are placed inside the cloak with an arbitrary distribution, the electric fields outside are purely determined by the total charges just as the fields of a point charge at the center of the cloak. As the total charges reduce to zero, the bodies can not be detected. On the other hand, if the total charges are nonzero, the electrostatic potential inside an ideal cloak tends to infinity. For unideal cloaks, this embarrassment is overcome, while they still have good behaviors of shielding. In addition, the potential across the inner surface of an ideal cloak is discontinuous due to the infinite polarization of the dielectric, however it can be alternatively interpreted as the dual Meissner effect of a dual superconductive layer with a surface magnetic current.
A Carpet Cloak Device for Visible Light
Gharghi, Majid; Zentgraf, Thomas; Liu, Yongmin; Yin, Xiaobo; Valentine, Jason; Zhang, Xiang
2011-01-01
We report an invisibility carpet cloak device, which is capable of making an object undetectable by visible light. The cloak is designed using quasi conformal mapping and is fabricated in a silicon nitride waveguide on a specially developed nano-porous silicon oxide substrate with a very low refractive index. The spatial index variation is realized by etching holes of various sizes in the nitride layer at deep subwavelength scale creating a local effective medium index. The fabricated device demonstrates wideband invisibility throughout the visible spectrum with low loss. This silicon nitride on low index substrate can also be a general scheme for implementation of transformation optical devices at visible frequency.
On directionality of phrase structure building.
Chesi, Cristiano
2015-02-01
Minimalism in grammatical theorizing (Chomsky in The minimalist program. MIT Press, Cambridge, 1995) led to simpler linguistic devices and a better focalization of the core properties of the structure building engine: a lexicon and a free (recursive) phrase formation operation, dubbed Merge, are the basic components that serve in building syntactic structures. Here I suggest that by looking at the elementary restrictions that apply to Merge (i.e., selection and licensing of functional features), we could conclude that a re-orientation of the syntactic derivation (from bottom-up/right-left to top-down/left-right) is necessary to make the theory simpler, especially for long-distance (filler-gap) dependencies, and is also empirically more adequate. If the structure building operations would assemble lexical items in the order they are pronounced (Phillips in Order and structure. PhD thesis, MIT, 1996; Chesi in Phases and cartography in linguistic computation: Toward a cognitively motivated computational model of linguistic competence. PhD thesis, Università di Siena, 2004; Chesi in Competence and computation: Toward a processing friendly minimalist grammar. Unipress, Padova, 2012), on-line performance data could better fit the grammatical model, without resorting to external "performance factors." The phase-based, top-down (and, as a consequence, left-right) Minimalist Grammar here discussed goes in this direction, ultimately showing how strong Islands (Huang in Logical relations in Chinese and the theory of grammar. PhD thesis, MIT, 1982) and intervention effects (Gordon et al. in J Exp Psychol Learn Mem Cogn 27:1411-1423, 2001, Gordon et al. in J Mem Lang 51:97-114, 2004) could be better explained in structural terms assuming this unconventional derivational direction. PMID:25408515
MODERN BUILDING STRUCTURES USED FOR MILITARY PURPOSES
Directory of Open Access Journals (Sweden)
Mariana Domnica STANCIU
2014-04-01
Full Text Available This paper investigates the technical aspects of the spherical spatial structures, focusing on the tensegrity building systems used for military purpose. The spherical spatial structures have been studied and used since antiquity. Pythagoras, Plato and Euclid were conducted extensive research on the concept of such type of structures. Regular pentagon has properties related to the value of the golden section, intuitively used by great architects and engineers since ancient times. In the Middle Ages, Leonardo Da Vinci created spatial objects using proportions based on the golden number, and later R. B. Fuller made the famous geodesic domes. The structures proposed by the authors are based on concepts related to the "golden section", on studies made on the regular pentagon, on the spatial volumes able to be inscribed in spheres and on the tensegrity systems. The proposed structures present some advantages related to the ease of mounting, to the volume covered, to the resistance to the environmental factors (snow, wind, earthquake, and so on. The paper presents the conclusions of the investigations on the components of the spatial structures and on the outcomes of their use.
Photorealistic rendering of unidirectional free-space invisibility cloaks
Halimeh, Jad C
2013-01-01
Carpet or ground-plane invisibility cloaks hide an object in reflection and inhibit transmission by construction. This concept has significantly reduced the otherwise demanding material requirements and has hence enabled various experimental demonstrations. In contrast, free-space invisibility cloaks should work in both reflection and transmission. The fabrication of omnidirectional three-dimensional free-space cloaks still poses significant challenges. Recently, the idea of the carpet cloak has been carried over to experiments on unidirectional free-space invisibility cloaks that only work perfectly for one particular viewing direction and, depending on the design, also for one linear polarization of light only. Here, by using photorealistic ray tracing, we visualize the performance of four types of such unidirectional cloaks in three dimensions for different viewing directions and different polarizations of light, revealing virtues and limitations of these approaches in an intuitive manner.
Two-Dimensional (2D) Polygonal Electromagnetic Cloaks
International Nuclear Information System (INIS)
Transformation optics offers remarkable control over electromagnetic fields and opens an exciting gateway to design 'invisible cloak devices' recently. We present an important class of two-dimensional (2D) cloaks with polygon geometries. Explicit expressions of transformed medium parameters are derived with their unique properties investigated. It is found that the elements of diagonalized permittivity tensors are always positive within an irregular polygon cloak besides one element diverges to plus infinity and the other two become zero at the inner boundary. At most positions, the principle axes of permittivity tensors do not align with position vectors. An irregular polygon cloak is designed and its invisibility to external electromagnetic waves is numerically verified. Since polygon cloaks can be tailored to resemble any objects, the transformation is finally generalized to the realization of 2D cloaks with arbitrary geometries. (fundamental areas of phenomenology (including applications))
Nonsingularity in two-dimensional cylindrical invisible cloaks
International Nuclear Information System (INIS)
The method of designing electromagnetic invisible cloaks is usually based on the form-invariance of Maxwell's equations in coordinate transformation. The exterior boundary of a cylindrical invisible cloak is unchanged and the interior boundary is extended from that of a point to that of a cylindrical region in coordination transformation. This transformation process makes perfect cloaks, but it causes singularity in the constitutive material parameters of cloaks. This singularity makes the cloaks impossible to realize in practice. In order to remove this singularity, this paper sets a small cylindrical region replacing a point in the space transformation. The cylindrical region is so small that it does not affect the invisibility effects, but it can remove the singularity for material parameters. Full wave simulations based on the finite element method were used to verify the designed cloaks. (classical areas of phenomenology)
An elasto-mechanical unfeelability cloak made of pentamode metamaterials.
Bückmann, T; Thiel, M; Kadic, M; Schittny, R; Wegener, M
2014-01-01
Metamaterial-based cloaks make objects different from their surrounding appear just like their surrounding. To date, cloaking has been demonstrated experimentally in many fields of research, including electrodynamics at microwave frequencies, optics, static electric conduction, acoustics, fluid dynamics, thermodynamics and quasi two-dimensional solid mechanics. However, cloaking in the seemingly simple case of three-dimensional solid mechanics is more demanding. Here, inspired by invisible core-shell nanoparticles in optics, we design an approximate elasto-mechanical core-shell 'unfeelability' cloak based on pentamode metamaterials. The resulting three-dimensional polymer microstructures with macroscopic overall volume are fabricated by rapid dip-in direct laser writing optical lithography. We quasi-statically deform cloak and control samples in the linear regime and map the displacement fields by autocorrelation-based analysis of recorded movies. The measured and the calculated displacement fields show very good cloaking performance. This means that one can elastically hide objects along these lines. PMID:24942191
Nonideal ultrathin mantle cloak for electrically large conducting cylinders.
Liu, Shuo; Zhang, Hao Chi; Xu, He-Xiu; Cui, Tie Jun
2014-09-01
Based on the concept of the scattering cancellation technique, we propose a nonideal ultrathin mantle cloak that can efficiently suppress the total scattering cross sections of an electrically large conducting cylinder (over one free-space wavelength). The cloaking mechanism is investigated in depth based on the Mie scattering theory and is simultaneously interpreted from the perspective of far-field bistatic scattering and near-field distributions. We remark that, unlike the perfect transformation-optics-based cloak, this nonideal cloaking technique is mainly designed to minimize simultaneously several scattering multipoles of a relatively large geometry around considerably broad bandwidth. Numerical simulations and experimental results show that the antiscattering ability of the metasurface gives rise to excellent total scattering reduction of the electrically large cylinder and remarkable electric-field restoration around the cloak. The outstanding cloaking performance together with the good features of and ultralow profile, flexibility, and easy fabrication predict promising applications in the microwave frequencies. PMID:25401449
Theory and optimization of transformation-based quadratic spherical cloaks
Novitsky, Andrey; Qiu, Cheng-Wei
2009-01-01
Based on the concept of the cloak generating function, we propose a numerical method to compute the invisibility performance of various quadratic spherical cloaks and obtain optimal invisibility results. A non-ideal discrete model is used to calculate and optimize the total scattering cross-sections of different profiles of the generating function. A bell-shaped quadratic spherical cloak is found to be the best candidate, which is further optimized by controlling design parameters involved. S...
A rigorous analysis of high order electromagnetic invisibility cloaks
Weder, Ricardo
2007-01-01
There is currently a great deal of interest in the invisibility cloaks recently proposed by Pendry et al. that are based in the transformation approach. They obtained their results using first order transformations. In recent papers Hendi et al. and Cai et al. considered invisibility cloaks with high order transformations. In this paper we study high order electromagnetic invisibility cloaks in transformation media obtained by high order transformations from general anisotropic media. We cons...
Cylindrical Cloak with Axial Permittivity/Permeability Spatially Invariant
Luo, Yu; Zhang, Jingjing; Chen, Hongsheng; Xi, Sheng; Wu, Bae-Ian
2008-01-01
In order to reduce the difficulties in the experimental realizations of the cloak but still keep good performance of invisibility, we proposed a perfect cylindrical invisibility cloak with spatially invariant axial material parameters. The advantage of this kind of TE (or TM) cloak is that only rho and phi components of mu (or epsilon) are spatially variant, which makes it possible to realize perfect invisibility with two-dimensional (2D) magnetic (or electric) metamaterials. The effects of p...
Experiments on metasurface carpet cloaking for audible acoustics
Faure, Cédric; Richoux, Olivier; Félix, Simon; Pagneux, Vincent
2016-02-01
We present experiments on acoustic carpet cloaking by using a metasurface made of graded Helmholtz resonators. The thin metasurface, placed over the object to hide, is designed such that the reflection phase shifts of the resonators at the resonance frequency are tuned to compensate the shape of the object to cloak. Experimental as well as numerical results show the efficiency of the cloak at the resonance frequency. The reflection of a short pulse is also reported to inspect the broadband character of the cloak.
Nonsingular cylindrical cloaks with internal–external invisible regions
International Nuclear Information System (INIS)
Two-dimensional nonsingular cloaks with internal and external invisible regions are presented. Objects can be hidden either in the internal cavity or the external concealment regions without being detected. Also in the latter case, the cloaked objects can receive incoming signals. In order to avoid the singularity (an infinitely large value of the constitutive parameters) which may appear at the inner boundary, the method of adjusting the principal stretches out of the cloaking plane is adopted. Detailed examples and their electromagnetic simulations are presented to validate the design. In addition, the effect of the material loss on the invisible property of the cloaks is also discussed
Lan, Lu; Liu, Yichao; Ong, C K; Ma, Yungui
2013-01-01
Electromagnetic invisible devices usually designed by transformation optics are rather complicated in material parameters and not suitable for general applications. Recently a topology optimized cloak based on level-set method was proposed to realize nearly perfect cloaking by Fujii et al [Appl. Phys. Lett. 102, 251106 (2013)]. In this work we experimentally implemented this idea and fabricated a unidirectional cloak with a relative large invisible region made of single dielectric material. Good cloaking performance was verified through measurement which consists very well with numerical simulation. The advantages and disadvantages of this optimization method are also discussed.
Structural acceptance criteria Remote Handling Building Tritium Extraction Facility
International Nuclear Information System (INIS)
This structural acceptance criteria contains the requirements for the structural analysis and design of the Remote Handling Building (RHB) in the Tritium Extraction Facility (TEF). The purpose of this acceptance criteria is to identify the specific criteria and methods that will ensure a structurally robust building that will safely perform its intended function and comply with the applicable Department of Energy (DOE) structural requirements
Structural acceptance criteria Remote Handling Building Tritium Extraction Facility
Energy Technology Data Exchange (ETDEWEB)
Mertz, G.
1999-12-16
This structural acceptance criteria contains the requirements for the structural analysis and design of the Remote Handling Building (RHB) in the Tritium Extraction Facility (TEF). The purpose of this acceptance criteria is to identify the specific criteria and methods that will ensure a structurally robust building that will safely perform its intended function and comply with the applicable Department of Energy (DOE) structural requirements.
Magnetic sensor for building structural vibrations.
García, Alfonso; Morón, Carlos; Tremps, Enrique
2014-01-01
This paper shows a new displacement-to-frequency transducer based on the variation of a coil inductance when a magnetic core is partially or completely inserted inside. This transducer is based on a Colpitts oscillator due its low manufacturing price, behavior and immunity to noise. A tank circuit with a configuration in parallel was used because it can be employed at lower frequencies and it enables it to make a direct analysis. The sensor has a dynamic range equal to the length of the coil. The cores can exchange sensors (coils with its ferromagnetic core) using the same electronic measuring system. In this way, with only an electronic circuit, the core sensor determines the measurement range. The obtained resolution is higher than 1/100,000, and the sensor also allows the measurement and knowing in real time the effect of vibration, thermal expansion, referred overload movements, etc.., that can occur in the structural elements of a building. PMID:24504104
Padooru, Yashwanth R.; Yakovlev, Alexander B.; Chen, Pai-Yen; Alù, Andrea
2012-08-01
Following the idea of "cloaking by a surface" [A. Alù, Phys. Rev. B 80, 245115 (2009); P. Y. Chen and A. Alù, Phys. Rev. B 84, 205110 (2011)], we present a rigorous analytical model applicable to mantle cloaking of cylindrical objects using 1D and 2D sub-wavelength conformal frequency selective surface (FSS) elements. The model is based on Lorenz-Mie scattering theory which utilizes the two-sided impedance boundary conditions at the interface of the sub-wavelength elements. The FSS arrays considered in this work are composed of 1D horizontal and vertical metallic strips and 2D printed (patches, Jerusalem crosses, and cross dipoles) and slotted structures (meshes, slot-Jerusalem crosses, and slot-cross dipoles). It is shown that the analytical grid-impedance expressions derived for the planar arrays of sub-wavelength elements may be successfully used to model and tailor the surface reactance of cylindrical conformal mantle cloaks. By properly tailoring the surface reactance of the cloak, the total scattering from the cylinder can be significantly reduced, thus rendering the object invisible over the range of frequencies of interest (i.e., at microwaves and far-infrared). The results obtained using our analytical model for mantle cloaks are validated against full-wave numerical simulations.
On three-dimensional spherical acoustic cloaking
Energy Technology Data Exchange (ETDEWEB)
Munteanu, Ligia; Chiroiu, Veturia, E-mail: ligia_munteanu@hotmail.com, E-mail: veturiachiroiu@yahoo.com [Institute of Solid Mechanics, Romanian Academy, 15 Constantin Mille, PO Box 1-863, 010141 Bucharest (Romania)
2011-08-15
Transformation acoustics opens a new avenue towards the design of acoustic metamaterials, which are materials engineered at the subwavelength scale in order to mimic the parameters in wave equations. The design of the acoustic cloaking is based on the property of equations being invariant under a coordinate transformation, i.e. a specific spatial compression is equivalent to a variation of the material parameters in the original space. In this paper, the sound invisibility performance is discussed for spherical cloaks. The original domain consists of alternating concentric layers made from piezoelectric ceramics and epoxy resin, following a triadic Cantor sequence. The spatial compression, obtained by applying the concave-down transformation, leads to an equivalent domain with an inhomogeneous and anisotropic distribution of the material parameters.
On three-dimensional spherical acoustic cloaking
International Nuclear Information System (INIS)
Transformation acoustics opens a new avenue towards the design of acoustic metamaterials, which are materials engineered at the subwavelength scale in order to mimic the parameters in wave equations. The design of the acoustic cloaking is based on the property of equations being invariant under a coordinate transformation, i.e. a specific spatial compression is equivalent to a variation of the material parameters in the original space. In this paper, the sound invisibility performance is discussed for spherical cloaks. The original domain consists of alternating concentric layers made from piezoelectric ceramics and epoxy resin, following a triadic Cantor sequence. The spatial compression, obtained by applying the concave-down transformation, leads to an equivalent domain with an inhomogeneous and anisotropic distribution of the material parameters.
Experimental demonstration of a bilayer thermal cloak.
Han, Tiancheng; Bai, Xue; Gao, Dongliang; Thong, John T L; Li, Baowen; Qiu, Cheng-Wei
2014-02-01
Invisibility has attracted intensive research in various communities, e.g., optics, electromagnetics, acoustics, thermodynamics, dc, etc. However, many experimental demonstrations have only been achieved by virtue of simplified approaches due to the inhomogeneous and extreme parameters imposed by the transformation-optic method, and usually require a challenging realization with metamaterials. In this Letter, we demonstrate a bilayer thermal cloak made of bulk isotropic materials, and it has been validated as an exact cloak. We experimentally verified its ability to maintain the heat front and its heat protection capabilities in a 2D proof-of-concept experiment. The robustness of this scheme is validated in both 2D (including oblique heat front incidence) and 3D configurations. The proposed scheme may open a new avenue to control the diffusive heat flow in ways inconceivable with phonons, and also inspire new alternatives to the functionalities promised by transformation optics. PMID:24580600
Experimental acoustic ground cloak in air.
Popa, Bogdan-Ioan; Zigoneanu, Lucian; Cummer, Steven A
2011-06-24
We present the design, fabrication, and performance analysis for a class of two-dimensional acoustic cloaking coatings in air. Our approach takes advantage of transformation acoustics and linear coordinate transformations that result in shells which are homogeneous, broadband, and compact. The required material parameters are highly anisotropic; however, we show that they are easily achievable in practice in metamaterials made of perforated plastic plates. The good performance of the fabricated design is assessed from measurements of the sound field produced around the cloak by a broadband source. The remarkably low complexity of the device made of perforated plastic plates shows that sound in air can be fully and effectively manipulated using realizable transformation acoustics devices. PMID:21770640
A cloaking device for transiting planets
Kipping, David M.; Teachey, Alex
2016-06-01
The transit method is presently the most successful planet discovery and characterization tool at our disposal. Other advanced civilizations would surely be aware of this technique and appreciate that their home planet's existence and habitability is essentially broadcast to all stars lying along their ecliptic plane. We suggest that advanced civilizations could cloak their presence, or deliberately broadcast it, through controlled laser emission. Such emission could distort the apparent shape of their transit light curves with relatively little energy, due to the collimated beam and relatively infrequent nature of transits. We estimate that humanity could cloak the Earth from Kepler-like broad-band surveys using an optical monochromatic laser array emitting a peak power of ˜30 MW for ˜10 hours per year. A chromatic cloak, effective at all wavelengths, is more challenging requiring a large array of tunable lasers with a total power of ˜250 MW. Alternatively, a civilization could cloak only the atmospheric signatures associated with biological activity on their world, such as oxygen, which is achievable with a peak laser power of just ˜160 kW per transit. Finally, we suggest that the time of transit for optical Search for Extraterrestrial Intelligence (SETI) is analogous to the water-hole in radio SETI, providing a clear window in which observers may expect to communicate. Accordingly, we propose that a civilization may deliberately broadcast their technological capabilities by distorting their transit to an artificial shape, which serves as both a SETI beacon and a medium for data transmission. Such signatures could be readily searched in the archival data of transit surveys.
Building Points - MO 2012 New Madrid Structure Points (SHP)
NSGIC GIS Inventory (aka Ramona) — Missouri Structure Points are structure points generated from a two pass look over the 2007 State 2ft imagery. Unlike the structure footprints, the building point...
Building Points - MO 2012 Dunklin Structure Points (SHP)
NSGIC GIS Inventory (aka Ramona) — Missouri Structure Points are structure points generated from a two pass look over the 2007 State 2ft imagery. Unlike the structure footprints, the building point...
Building Points - MO 2012 Stoddard Structure Points (SHP)
NSGIC GIS Inventory (aka Ramona) — Missouri Structure Points are structure points generated from a two pass look over the 2007 State 2ft imagery. Unlike the structure footprints, the building point...
Building Points - MO 2012 Pemiscot Structure Points (SHP)
NSGIC GIS Inventory (aka Ramona) — Missouri Structure Points are structure points generated from a two pass look over the 2007 State 2ft imagery. Unlike the structure footprints, the building point...
Building Points - MO 2012 Mississippi Structure Points (SHP)
NSGIC GIS Inventory (aka Ramona) — Missouri Structure Points are structure points generated from a two pass look over the 2007 State 2ft imagery. Unlike the structure footprints, the building point...
Building Points - MO 2012 Scott Structure Points (SHP)
NSGIC GIS Inventory (aka Ramona) — Missouri Structure Points are structure points generated from a two pass look over the 2007 State 2ft imagery. Unlike the structure footprints, the building point...
Design Numerical Method for Nonsingular Invisibility Cloak-Carpet with Arbitrary Shapes
V.I. Vyunnik; A.A. Zvyagintsev
2012-01-01
The using of the nonsingular invisibility cloak similarly as invisibility carpet was proposed. The possibility of fully numerical approach to calculation arbitrary nonsingular invisibility cloak, by a choice of elliptic coordinate system during coordinate transformation, was shown. The numerical modeling nonsingular cloak and cloak-carpet of arbitrary form and the estimation of efficiency while using, was completed.
Design Numerical Method for Nonsingular Invisibility Cloak-Carpet with Arbitrary Shapes
Directory of Open Access Journals (Sweden)
V. I. Vyunnik
2012-11-01
Full Text Available The using of the nonsingular invisibility cloak similarly as invisibility carpet was proposed. The possibility of fully numerical approach to calculation arbitrary nonsingular invisibility cloak, by a choice of elliptic coordinate system during coordinate transformation, was shown. The numerical modeling nonsingular cloak and cloak-carpet of arbitrary form and the estimation of efficiency while using, was completed.
About the survey of building structures with signs of biodeterioration
Directory of Open Access Journals (Sweden)
S.A. Startsev
2010-11-01
Full Text Available In the article different types of biological destructors and mechanism of their influence on building structures are examined. Experience in the survey of masonry, brick, metal, wooden, reinforced-concrete buildings damaged or destroyed biologically is depicted. Recommendations for microbiological survey of buildings are given.
Simplified ground plane invisibility cloak by multilayer dielectrics.
Xu, Xiaofei; Feng, Yijun; Yu, Zhenzhong; Jiang, Tian; Zhao, Junming
2010-11-22
Most implementations of the ground plane invisibility cloak are based on the isotropic design through the quasi-conformal transformation. However recent theoretical analysis predicts the unavoidable lateral shift of the scattering fields associated with these cloaks making them detectable. In this paper, we propose an alternative method to design the ground plane invisibility clock with electromagnetic beam modulation blocks through simple coordinate transformation discussed in our previous work. The ground plane cloak obtained with the rigorous transformation optics possesses moderate anisotropic distributions of material parameters, but results in no lateral shift of the scattering fields. To realize the design, a possible scheme is suggested by discretizing the ground plane cloak to several homogeneous sub-blocks. These sub-blocks can be realized with multilayer isotropic dielectrics with alignment angles that are determined by the effective medium theory. Thus the non-magnetic ground plane invisibility cloak can be constructed by several multilayered normal dielectrics aligned in different angles. The performance of the proposed cloak and its practical implementation is validated by full-wave electromagnetic simulations with both near field distributions and far field scattering patterns under different EM wave incident angles. The proposed cloak is composed of normal dielectric multilayers, thus can leads to easy experimental demonstration of non-magnetic ground plane cloak in the frequency range from microwave to optical. PMID:21164794
Topology optimized low-contrast all-dielectric optical cloak
DEFF Research Database (Denmark)
Andkjær, Jacob Anders; Sigmund, Ole
2011-01-01
A systematic methodology for designing low-contrast all-dielectric cloaks operating in the optical range is presented. Topology optimization is used to find the layout of standard dielectric material that minimizes the norm of the scattered field in the surroundings of the cloak. Rotational symme...... than the noncloaked object. (C) 2011 American Institute of Physics. [doi:10.1063/1.3540687]...
Spontaneous emission and the operation of invisibility cloaks
Morshed Behbahani, Mina; Amooghorban, Ehsan; Mahdifar, Ali
2016-07-01
As a probe to explore the ability of invisibility cloaks to conceal objects in the quantum mechanics domain, we study the spontaneous emission rate of an excited two-level atom in the vicinity of an ideal invisibility cloaking. On this base, first, a canonical quantization scheme is presented for the electromagnetic field interacting with atomic systems in an anisotropic, inhomogeneous, and absorbing magnetodielectric medium which can suitably be used for studying the influence of arbitrary invisibility cloak on the atomic radiative properties. The time dependence of the atomic subsystem is obtained in the Schrodinger picture. By introducing a modified set of the spherical wave-vector functions, the Green tensor of the system is calculated via exact and discrete methods. In this formalism, the decay rate and as well the emission pattern of the aforementioned atom are computed analytically for both weak and strong coupling interaction, and then numerically calculations are done to demonstrate the performances of cloaking in the quantum mechanics domain. Special attention is paid to different possible orientations and locations of the atomic system near the spherical invisibility cloaking. Results in the presence and the absence of the invisibility cloak are compared. We find that the cloak works very well far from its resonance frequency to conceal a macroscopic object, whereas at near the resonance frequency the object is more visible than the situation where the object is not covered by the cloak.
Invisibility cloaking via non-smooth transformation optics and ray tracing
International Nuclear Information System (INIS)
We present examples of theoretically-predicted invisibility cloaks with shapes other than spheres and cylinders, including cones and ellipsoids, as well as shapes spliced from parts of these simpler shapes. In addition, we present an example explicitly displaying the non-uniqueness of invisibility cloaks of the same shape. We depict rays propagating through these example cloaks using ray tracing for geometric optics. - Highlights: → Theoretically-predicted conical and ellipsoidal invisibility cloaks. → Non-smooth cloaks spliced from parts of simpler shapes. → Example displaying non-uniqueness of invisibility cloaks of the same shape. → Rays propagating through example cloaks depicted using geometric optics.
Invisibility cloaking via non-smooth transformation optics and ray tracing
Energy Technology Data Exchange (ETDEWEB)
Crosskey, Miles M., E-mail: mmc31@duke.ed [Mathematics Department, Duke University, Box 90320, Durham, NC 27708-0320 (United States); Nixon, Andrew T., E-mail: andrew_nixon@brown.ed [Division of Applied Mathematics, Brown University, 182 George Street, Providence, RI 02912 (United States); Schick, Leland M., E-mail: lschick@math.arizona.ed [Department of Mathematics, University of Arizona, 617 N. Santa Rita Ave., P.O. Box 210089, Tucson, AZ 85721-0089 (United States); Kovacic, Gregor, E-mail: kovacg@rpi.ed [Mathematical Sciences Department, Rensselaer Polytechnic Institute, 110 8th Street, Troy, NY 12180 (United States)
2011-05-02
We present examples of theoretically-predicted invisibility cloaks with shapes other than spheres and cylinders, including cones and ellipsoids, as well as shapes spliced from parts of these simpler shapes. In addition, we present an example explicitly displaying the non-uniqueness of invisibility cloaks of the same shape. We depict rays propagating through these example cloaks using ray tracing for geometric optics. - Highlights: Theoretically-predicted conical and ellipsoidal invisibility cloaks. Non-smooth cloaks spliced from parts of simpler shapes. Example displaying non-uniqueness of invisibility cloaks of the same shape. Rays propagating through example cloaks depicted using geometric optics.
Omnidirectional surface wave cloak using an isotropic homogeneous dielectric coating
Mitchell-Thomas, R. C.; Quevedo-Teruel, O.; Sambles, J. R.; Hibbins, A. P.
2016-08-01
The field of transformation optics owes a lot of its fame to the concept of cloaking. While some experimental progress has been made towards free-space cloaking in three dimensions, the material properties required are inherently extremely difficult to achieve. The approximations that then have to be made to allow fabrication produce unsatisfactory device performance. In contrast, when surface wave systems are the focus, it has been shown that a route distinct from those used to design free-space cloaks can be taken. This results in very simple solutions that take advantage of the ability to incorporate surface curvature. Here, we provide a demonstration in the microwave regime of cloaking a bump in a surface. The distortion of the shape of the surface wave fronts due to the curvature is corrected with a suitable refractive index profile. The surface wave cloak is fabricated from a metallic backed homogeneous dielectric waveguide of varying thickness, and exhibits omnidirectional operation.
Hiding a Realistic Object Using a Broadband Terahertz Invisibility Cloak
Zhou, Fan; Cao, Wei; Stuart, Colin T; Gu, Jianqiang; Zhang, Weili; Sun, Cheng
2011-01-01
The invisibility cloak has been a long-standing dream for many researchers over the decades. The introduction of transformational optics has revitalized this field by providing a general method to design material distributions to hide the subject from detection. By transforming space and light propagation, a three-dimensional (3D) object is perceived as having a reduced number of dimensions, in the form of points, lines, and thin sheets, making it "undetectable" judging from the scattered field. Although a variety of cloaking devices have been reported at microwave and optical frequencies, the spectroscopically important Terahertz (THz) domain remains unexplored. Moreover, due to the difficulties in fabricating cloaking devices that are optically large in all three dimensions, hiding realistic 3D objects has yet to be demonstrated. Here, we report the first experimental demonstration of a 3D THz cloaking device fabricated using a scalable Projection Microstereolithography process. The cloak operates at a broa...
Numerical Analysis of Three-dimensional Acoustic Cloaks and Carpets
Dupont, Guillaume; Diatta, Andre; Guenneau, Sebastien; Enoch, Stefan
2011-01-01
We start by a review of the chronology of mathematical results on the Dirichlet-to-Neumann map which paved the way towards the physics of transformational acoustics. We then rederive the expression for the (anisotropic) density and bulk modulus appearing in the pressure wave equation written in the transformed coordinates. A spherical acoustic cloak consisting of an alternation of homogeneous isotropic concentric layers is further proposed based on the effective medium theory. This cloak is characterised by a low reflection and good efficiency over a large bandwidth for both near and far fields, which approximates the ideal cloak with a inhomogeneous and anisotropic distribution of material parameters. The latter suffers from singular material parameters on its inner surface. This singularity depends upon the sharpness of corners, if the cloak has an irregular boundary, e.g. a polyhedron cloak becomes more and more singular when the number of vertices increases if it is star shaped. We thus analyse the acoust...
Cloaking by shells with radially inhomogeneous anisotropic permittivity.
Reshetnyak, V Yu; Pinkevych, I P; Sluckin, T J; Evans, D R
2016-01-25
We model electromagnetic cloaking of a spherical or cylindrical nanoparticle enclosed by an optically anisotropic and optically inhomogeneous symmetric shell, by examining its electric response in a quasi-static uniform electric field. When the components of the shell permittivity are radially anisotropic and power-law dependent (ε~rm) whereris distance to the shell center, and m a positive or negative exponent which can be varied), the problem is analytically tractable. Formulas are calculated for the degree of cloaking in the general case, allowing the determination of a dielectric condition for the shells to be used as an invisibility cloak. Ideal cloaking is known to require that homogeneous shells exhibit an infinite ratio of tangential and radial components of the shell permittivity, but for radially inhomogeneous shells ideal cloaking can occur even for finite values of this ratio. PMID:26832575
Homogeneous thermal cloak with constant conductivity and tunable heat localization.
Han, Tiancheng; Yuan, Tao; Li, Baowen; Qiu, Cheng-Wei
2013-01-01
Invisible cloak has long captivated the popular conjecture and attracted intensive research in various communities of wave dynamics, e.g., optics, electromagnetics, acoustics, etc. However, their inhomogeneous and extreme parameters imposed by transformation-optic method will usually require challenging realization with metamaterials, resulting in narrow bandwidth, loss, polarization-dependence, etc. In this paper, we demonstrate that thermodynamic cloak can be achieved with homogeneous and finite conductivity only employing naturally available materials. It is demonstrated that the thermal localization inside the coating layer can be tuned and controlled robustly by anisotropy, which enables an incomplete cloak to function perfectly. Practical realization of such homogeneous thermal cloak has been suggested by using two naturally occurring conductive materials, which provides an unprecedentedly plausible way to flexibly realize thermal cloak and manipulate heat flow with phonons. PMID:23549139
Metasurface Cloak Performance Near-by Multiple Line Sources and PEC Cylindrical Objects
DEFF Research Database (Denmark)
Arslanagic, Samel; Yatman, William H.; Pehrson, Signe;
2014-01-01
The performance/robustness of metasurface cloaks to a complex field environment which may represent a realistic scenario of radiating sources is presently reported. Attention is devoted to the cloak operation near-by multiple line sources and multiple perfectly electrically conducting cylinders. It...... is shown that the metasurface cloaks, initially designed to cloak an isolated dielectric cylinder excited by a single line source, retain their ability to cloak in these new, more realistic, excitation cases....
Amemiya, Tomohiro; Taki, Masato
2012-01-01
Is it possible to actually make Harry's invisibility cloaks? The most promising approach for realizing such magical cloaking in our real world would be to use transformation optics, where an empty space with a distorted geometry is imitated with a non-distorted space but filled with transformation medium having appropriate permittivity and permeability. An important requirement for practical invisibility cloaks is nonreciprocity; that is, a person in the cloak should not be seen from the outside but should be able to see the outside. This invisibility cloak, or a nonreciprocal shield, cannot be created as far as we stay in conventional transformation optics. Conventional transformation optics is based on Riemann geometry with a metric tensor independent of direction, and therefore cannot be used to design the nonreciprocal shield. To overcome this problem, we propose an improved theory of transformation optics that is based on Finsler geometry, an extended version of Riemann geometry. Our theory shows that no...
Energy Technology Data Exchange (ETDEWEB)
Healey, J.J.; Wu, S.T.; Murga, M.
1980-02-01
As part of the Phase I effort of the Seismic Safety Margins Research Program (SSMRP) being performed by the University of California Lawrence Livermore Laboratory for the US Nuclear Regulatory Commission, the basic objective of Subtask IV.1 (Structural Building Response Review) is to review and summarize current methods and data pertaining to seismic response calculations particularly as they relate to the objectives of the SSMRP. This material forms one component in the development of the overall computational methodology involving state of the art computations including explicit consideration of uncertainty and aimed at ultimately deriving estimates of the probability of radioactive releases due to seismic effects on nuclear power plant facilities.
International Nuclear Information System (INIS)
As part of the Phase I effort of the Seismic Safety Margins Research Program (SSMRP) being performed by the University of California Lawrence Livermore Laboratory for the US Nuclear Regulatory Commission, the basic objective of Subtask IV.1 (Structural Building Response Review) is to review and summarize current methods and data pertaining to seismic response calculations particularly as they relate to the objectives of the SSMRP. This material forms one component in the development of the overall computational methodology involving state of the art computations including explicit consideration of uncertainty and aimed at ultimately deriving estimates of the probability of radioactive releases due to seismic effects on nuclear power plant facilities
The effect of electrostatic shielding using invisibility cloak
Directory of Open Access Journals (Sweden)
Ruo-Yang Zhang
2011-12-01
Full Text Available The effect of electrostatic shielding for a spherical invisibility cloak with arbitrary charges inside is investigated. Our result reveals that the charge inside the cloak is a crucial factor to determine the detection. When charged bodies are placed inside the cloak with an arbitrary distribution, the electric fields outside are purely determined by the total charges just as the fields of a point charge at the center of the cloak. As the total charges reduce to zero, the bodies can not be detected. On the other hand, if the total charges are nonzero, the electrostatic potential inside an ideal cloak tends to infinity. For unideal cloaks, this embarrassment is overcome, while they still have good behaviors of shielding. In addition, the potential across the inner surface of an ideal cloak is discontinuous due to the infinite polarization of the dielectric, however it can be alternatively interpreted as the dual Meissner effect of a dual superconductive layer with a surface magnetic current.
International Nuclear Information System (INIS)
The highly automated PHENIX AutoBuild wizard is described. The procedure can be applied equally well to phases derived from isomorphous/anomalous and molecular-replacement methods. The PHENIX AutoBuild wizard is a highly automated tool for iterative model building, structure refinement and density modification using RESOLVE model building, RESOLVE statistical density modification and phenix.refine structure refinement. Recent advances in the AutoBuild wizard and phenix.refine include automated detection and application of NCS from models as they are built, extensive model-completion algorithms and automated solvent-molecule picking. Model-completion algorithms in the AutoBuild wizard include loop building, crossovers between chains in different models of a structure and side-chain optimization. The AutoBuild wizard has been applied to a set of 48 structures at resolutions ranging from 1.1 to 3.2 Å, resulting in a mean R factor of 0.24 and a mean free R factor of 0.29. The R factor of the final model is dependent on the quality of the starting electron density and is relatively independent of resolution
Structural Reforms, IMF Programs and Capacity Building; An Empirical Investigation
Rabah Arezki; Marc Quintyn; Frederik G Toscani
2012-01-01
This paper investigates the role that International Monetary Fund (IMF) programs and capacity building play in fostering structural reforms. To do so, we exploit two novel datasets on IMF capacity building and structural reforms available for over one hundred IMF member countries over the period 1980 - 2010. The main results are threefold. First, there is a general association between IMF programs and structural reforms but this relationship is not very robust. Second, IMF training leads to a...
Aharonov-Bohm detection of two-dimensional magnetostatic cloaks
Valagiannopoulos, Constantinos A.; Askarpour, Amir Nader; Alù, Andrea
2015-12-01
Two-dimensional magnetostatic cloaks, even when perfectly designed to mitigate the magnetic field disturbance of a scatterer, may be still detectable with Aharonov-Bohm (AB) measurements, and therefore may affect quantum interactions and experiments with elongated objects. We explore a multilayered cylindrical cloak whose permeability profile is tailored to nullify the magnetic-flux perturbation of the system, neutralizing its effect on AB measurements, and simultaneously optimally suppress the overall scattering. In this way, our improved magnetostatic cloak combines substantial mitigation of the magnetostatic scattering response with zero detectability by AB experiments.
Optimization of multilayer cylindrical cloaks using genetic algorithms and NEWUOA
Sakr, Ahmed A.; Abdelmageed, Alaa K.
2016-06-01
The problem of minimizing the scattering from a multilayer cylindrical cloak is studied. Both TM and TE polarizations are considered. A two-stage optimization procedure using genetic algorithms and NEWUOA (new unconstrained optimization algorithm) is adopted for realizing the cloak using homogeneous isotropic layers. The layers are arranged such that they follow a repeated pattern of alternating DPS and DNG materials. The results show that a good level of invisibility can be realized using a reasonable number of layers. Maintaining the cloak performance over a finite range of frequencies without sacrificing the level of invisibility is achieved.
Wind-resistant studies on tall buildings and structures
Institute of Scientific and Technical Information of China (English)
无
2010-01-01
This paper introduces some aspects of wind-resistant studies of our research team on tall buildings and structures. Wind tunnel tests were carried out on 27 typical tall building models by using wind pressure scanning and HFFB techniques. The characteristics of wind pressures and forces acting on these buildings were analyzed. Some results have been adopted in a Shanghai code for structural design of steel tall buildings. Interference effects on wind forces and wind pressures among two and three tall buildings were experimentally investigated with about 10000 testing conditions. Regression analyses of the interference factors under different parameter conditions were made and the main regression formulas are presented. Theoretical study on equivalent static wind loads of tall buildings and structures are then introduced. Especially,a new concept of "mode coupling factor" and a modified SRSS method for wind response and equivalent static wind load of complicated tall buildings and structures with consideration of multi mode contributions and their coupling effects are presented. Finally,practical applications of wind-resistant studies on tall building and structures,taking the Guangzhou New TV Tower as an example,are presented.
Building Footprints - Montana Structures/Addresses Framework
NSGIC GIS Inventory (aka Ramona) — The Montana Structures/Addresses Framework is a statewide spatial database of structure and address points in the State of Montana. The Montana Structures/Addresses...
Leadership: Building a Team Using Structured Activities
Rivas, Olivia; Jones, Irma S.
2012-01-01
Educators strive to anticipate reactions or outcomes of instruction so that the learning or acquiring of information by others is as pain-free as possible. Leaders also strive to build cohesiveness and trust in groups or teams of employees so that the end goal or task is produced in a timely manner. However, setting the stage or mood for teamwork…
Acoustic cloaking and mirages with flying carpets
Diatta, Andre; Guenneau, Sebastien; Enoch, Stefan
2009-01-01
Carpets under consideration here, in the context of pressure acoustic waves propagating in a compressible fluid, do not touch the ground: they levitate in mid-air (or float in mid-water), which leads to approximate cloaking for an object hidden underneath, or touching either sides of a square cylinder on, or over, the ground. The tentlike carpets attached to the sides of a square cylinder illustrate how the notion of a carpet on a wall naturally generalizes to sides of other small compact objects. We then extend the concept of flying carpets to circular cylinders. However, instead of reducing its scattering cross-section like in acoustic cloaks, we rather mimic that of another obstacle, say a square rigid cylinder. For instance, show that one can hide any type of defects under such circular carpets, and yet they still scatter waves just like a smaller cylinder on its own. Interestingly, all these carpets are described by non-singular acoustic parameters. To exemplify this important aspect, we propose a multi-...
Environmental effect of structural solutions and building materials to a building
International Nuclear Information System (INIS)
The field of building environmental assessment tools has become a popular research area over the past decade. However, how the service life of a building affects the results of the environmental assessment of a building has not been emphasised previously. The aim of this study is to analyse how different structural solutions and building materials affect the results of the environmental assessment of a whole building over the building's life cycle. Furthermore, how the length of the building's service life affects the results is analysed. The environmental assessments of 78 single-family houses were calculated for this study. The buildings have different wall insulations, claddings, window frames, and roof materials, and the length of the service life varies from 60 years up to 160 years. The current situation and the future of the environmental assessment of buildings are discussed. In addition, topics for further research are suggested; for example, how workmanship affects the service life and the environmental impact of a building should be studied
Structural evaluation of the 2736Z Building for seismic loads
International Nuclear Information System (INIS)
The 2736Z building structure is evaluated for high-hazard loads. The 2736Z building is analyzed herein for normal and seismic loads and is found to successfully meet the guidelines of UCRL-15910 along with the related codes requirements
Building with electromagnetic shield structure for individual floors
International Nuclear Information System (INIS)
This invention relates to a building having a floor-by-floor electromagnetic shield structure well-suited for application to an information network system in which an electromagnetically shielded space is divided by individual floors and electric waves are utilized within the building on a floor-by-floor basis. (author). 8 figs
Building Investigation: Material or Structural Performance
Yusof M.Z.
2014-01-01
Structures such as roof trusses will not suddenly collapse without ample warning such as significant deflection, tilting etc. if the designer manages to avoid the cause of structural failure at the material level and the structural level. This paper outlines some principles and procedures of PDCA circle and QC tools which can show some clues of structural problems in terms of material or structural performance
Building Investigation: Material or Structural Performance
Directory of Open Access Journals (Sweden)
Yusof M.Z.
2014-03-01
Full Text Available Structures such as roof trusses will not suddenly collapse without ample warning such as significant deflection, tilting etc. if the designer manages to avoid the cause of structural failure at the material level and the structural level. This paper outlines some principles and procedures of PDCA circle and QC tools which can show some clues of structural problems in terms of material or structural performance
Energy Technology Data Exchange (ETDEWEB)
Los Alamos National Laboratory, Mailstop M888, Los Alamos, NM 87545, USA; Lawrence Berkeley National Laboratory, One Cyclotron Road, Building 64R0121, Berkeley, CA 94720, USA; Department of Haematology, University of Cambridge, Cambridge CB2 0XY, England; Terwilliger, Thomas; Terwilliger, T.C.; Grosse-Kunstleve, Ralf Wilhelm; Afonine, P.V.; Moriarty, N.W.; Zwart, P.H.; Hung, L.-W.; Read, R.J.; Adams, P.D.
2007-04-29
The PHENIX AutoBuild Wizard is a highly automated tool for iterative model-building, structure refinement and density modification using RESOLVE or TEXTAL model-building, RESOLVE statistical density modification, and phenix.refine structure refinement. Recent advances in the AutoBuild Wizard and phenix.refine include automated detection and application of NCS from models as they are built, extensive model completion algorithms, and automated solvent molecule picking. Model completion algorithms in the AutoBuild Wizard include loop-building, crossovers between chains in different models of a structure, and side-chain optimization. The AutoBuild Wizard has been applied to a set of 48 structures at resolutions ranging from 1.1 {angstrom} to 3.2 {angstrom}, resulting in a mean R-factor of 0.24 and a mean free R factor of 0.29. The R-factor of the final model is dependent on the quality of the starting electron density, and relatively independent of resolution.
Impact of climate change on building structures
Czech Academy of Sciences Publication Activity Database
Drdácký, Miloš
Bari : EDIPUGLIA, 2010 - (Lefebre, R.; Sabbioni, C.), s. 139-153 ISBN 978-88-7228-601-2 R&D Projects: GA ČR(CZ) GA103/09/2067 Grant ostatní: evropská komise(XE) 6th FP EC CHEF -044251 Institutional research plan: CEZ:AV0Z20710524 Keywords : climate change impact * weathering * vulnerability of buildings Subject RIV: AL - Art, Architecture, Cultural Heritage
Achieving acoustic cloak by using compressible background flow
Zhang, Ruo-Yang; Ge, Mo-Lin
2016-01-01
We propose a scheme of acoustic spherical cloaking by means of background irrotational flow in compressible fluid. The background flow forms a virtual curved spacetime and guides the sound waves bypass the cloaked objects. To satisfy the laws of real fluid, we show that spatially distributed mass source and momentum source are necessary to supply. The propagation of sound waves in this system is studied via both geometric acoustics approximation and full wave approach. The analytic solution of sound fields is obtained for plane wave incidence. The results reveal the effect of phase retardation (or lead) in comparison with the ordinary transformation-acoustic cloak. In addition, the ability of cloaking is also evaluated for unideal background flows by analyzing the scattering cross section.
Diffuse-light all-solid-state invisibility cloak.
Schittny, Robert; Niemeyer, Andreas; Kadic, Muamer; Bückmann, Tiemo; Naber, Andreas; Wegener, Martin
2015-09-15
An ideal invisibility cloak makes arbitrary macroscopic objects within the cloak indistinguishable from its surrounding—for all directions, illumination patterns, polarizations, and colors of visible light. Recently, we have approached such an ideal cloak for the diffusive regime of light propagation using a core-shell geometry and a mixture of water and white wall paint as the surrounding. Here, we present an all-solid-state version based on polydimethylsiloxane doped with titania nanoparticles for the surrounding/shell and on a high-reflectivity microporous ceramic for the core. By virtue of reduced effects of absorption, especially from the core, the cloaking performance and the overall light throughput are improved significantly. PMID:26371896
Achieving acoustic cloak by using compressible background flow
Zhang, Ruo-Yang; Zhao, Qing; Ge, Mo-Lin
2016-08-01
We propose a scheme of acoustic spherical cloaking by means of background irrotational flow in compressible fluid. The background flow forms a virtual curved spacetime and directs the sound waves to bypass the cloaked objects. To satisfy the laws of real fluid, we show that spatially distributed mass source and momentum source are necessary to supply. The propagation of sound waves in this system is studied via both geometric acoustics approximation and full wave approach. The analytic solution of sound fields is obtained for plane wave incidence. The results reveal the effect of phase retardation (or lead) in comparison with the ordinary transformation-acoustic cloak. In addition, the ability of cloaking is also evaluated for unideal background flows by analyzing the scattering cross section. Project supported by the National Natural Science Foundation of China (Grant Nos. 11475088 and 11275024) and the Fund from the Ministry of Science and Technology of China (Grant No. 2013YQ030595-3).
Active cloaking for clusters of pins in thin plates
O'Neill, Jane; Haslinger, Stewart; Movchan, Natasha; Craster, Richard
2016-01-01
This paper considers active cloaking of a square array of evenly spaced pins in a Kirchhoff plate in the presence of flexural waves. Active sources are distributed exterior to the cluster and are represented by the non-singular Green's function for the biharmonic operator. The complex amplitudes of the active sources, which cancel out selected multipole orders of the scattered field, are found by solving an algebraic system of equations. For frequencies in the zero-frequency stop band, we find that a small number of active sources located on a grid is sufficient for cloaking. For higher frequencies, we achieve efficient cloaking with the active sources positioned on a circle surrounding the cluster. We demonstrate the cloaking efficiency with several numerical illustrations, considering key frequencies from band diagrams and dispersion surfaces for a Kirchhoff plate pinned in a doubly periodic fashion.
Innovated Building Material's Interactions with Structural Form in Architectural Projects
Mozaikci, Begüm
2009-01-01
ABSTRACT: Interpretation of building materials into architectural form, is gaining greater interest and attention due to the conservation of architectural heritage. This study highlight, the influences of technological developments of building materials and their interactions with structural form in architectural design projects. Architectural form and decisions can potentially effects by introduced new materials and this study focus on the interaction of new material and structural form...
Soil Structure Interaction between Two Adjacent Buildings under Earthquake Load
Mahmoud Yahyai; Masoud Mirtaheri; Mehrab Mahoutian; Amir S. Daryan
2008-01-01
In some cases, tall buildings are located in geotechnically unsuitable places, due to their high ratio of height to width; there is risk of uplift and other effects such as overturning and reduction structure serviceability during earthquake. This research is aimed to evaluate the effect of Soil-Structure Interaction (SSI) on seismic behavior of two adjacent 32 story buildings such as time period, base shear and displacements. The interaction effects are investigated for variable distance bet...
A metasurface carpet cloak for electromagnetic, acoustic and water waves
Yihao Yang; Huaping Wang; Faxin Yu; Zhiwei Xu; Hongsheng Chen
2016-01-01
We propose a single low-profile skin metasurface carpet cloak to hide objects with arbitrary shape and size under three different waves, i.e., electromagnetic (EM) waves, acoustic waves and water waves. We first present a metasurface which can control the local reflection phase of these three waves. By taking advantage of this metasurface, we then design a metasurface carpet cloak which provides an additional phase to compensate the phase distortion introduced by a bump, thus restoring the re...
Creation of Tunable Homogeneous Thermal Cloak with Constant Conductivity
Han, Tiancheng; Li, Baowen; Qiu, Cheng-Wei
2013-01-01
Invisible cloak has long captivated the popular conjecture and attracted intensive research in various communities of wave dynamics, e.g., optics, electromagnetics, acoustics, etc. However, their inhomogeneous and extreme parameters imposed by transformation-optic method will usually require challenging realization with metamaterials, resulting in narrow bandwidth, loss, polarization-dependence, etc. On the contrary, we demonstrate that tunable thermodynamic cloak can be achieved with homogen...
Homogeneous Thermal Cloak with Constant Conductivity and Tunable Heat Localization
Han, Tiancheng; Yuan, Tao; Li, Baowen; Qiu, Cheng-Wei
2013-01-01
Invisible cloak has long captivated the popular conjecture and attracted intensive research in various communities of wave dynamics, e.g., optics, electromagnetics, acoustics, etc. However, their inhomogeneous and extreme parameters imposed by transformation-optic method will usually require challenging realization with metamaterials, resulting in narrow bandwidth, loss, polarization-dependence, etc. In this paper, we demonstrate that thermodynamic cloak can be achieved with homogeneous and f...
Thermal invisibility based on scattering cancellation and mantle cloaking
Farhat, M.; Chen, P.-Y.; H. Bagci; Amra, Claude; Guenneau, Sébastien; Alu, A.
2015-01-01
We theoretically and numerically analyze thermal invisibility based on the concept of scattering cancellation and mantle cloaking. We show that a small object can be made completely invisible to heat diffusion waves, by tailoring the heat conductivity of the spherical shell enclosing the object. This means that the thermal scattering from the object is suppressed, and the heat flow outside the object and the cloak made of these spherical shells behaves as if the object is not present. Thermal...
Time-of-flight imaging of invisibility cloaks
Halimeh, Jad C.; Wegener, Martin
2012-01-01
As invisibility cloaking has recently become experimental reality, it is interesting to explore ways to reveal remaining imperfections. In essence, the idea of most invisibility cloaks is to recover the optical path lengths without an object (to be made invisible) by a suitable arrangement around that object. Optical path length is proportional to the time of flight of a light ray or to the optical phase accumulated by a light wave. Thus, time-of-flight images provide a direct and intuitive t...
The simplified material parameter equation for elliptical cylinder cloaks
Institute of Scientific and Technical Information of China (English)
Ma Hua; Qu Shao-Bo; Xu Zhuo; Zhang Jie-Qiu; Wang Jia-Fu
2009-01-01
We simplify the material parameter equation for elliptical cylinder cloaks under transverse-electric and transverse-magnetic modcis, respectively, and confirm these simplified equations by numerical simulations. As a result, the number of the component parameters is reduced from three to two, which simplifies the design of meta-materials and thus opens up the possibility of achieving elliptical cylinder cloaks in an easy way.
Push-Over Analysis for Concrete Structures of Tall Building
Institute of Scientific and Technical Information of China (English)
朱杰江; 张佩军; 吕西林; 容柏生
2004-01-01
In this paper, push-over analysis for tall concrete structures was made and a corresponding computer program was given.Several kinds of elements in the program were considered to meet the demand of tall buildings with complex structural type. These elements included beam-column element for beams and columns, single slice wall element and three vertical line element for walls, and tube-wall element for tubes. Computational example for verifying the models indicates that the result obtained by this method is identical with a well-known test result and the program can be used to search for the full process of structural reaction, even the softening stage of the structure. With this push-over analysis method, an actual tall building with complex structural type was analyzed, and the result has been put into practice of the structural design of the building.
Tunable scattering cancellation cloak with plasmonic ellipsoids in the visible
Fruhnert, Martin; Monti, Alessio; Fernandez-Corbaton, Ivan; Alù, Andrea; Toscano, Alessandro; Bilotti, Filiberto; Rockstuhl, Carsten
2016-06-01
The scattering cancellation technique is a powerful tool to reduce the scattered field from electrically small objects in a specific frequency window. The technique relies on covering the object of interest with a shell that scatters light into a far field of equal strength as the object but with a phase shift of π . The resulting destructive interference prohibits its detection in measurements that probe the scattered light. Whereas at radio or microwave frequencies feasible designs have been proposed that allow us to tune the operational frequency upon request, similar capabilities have not yet been explored in the visible. However, such an ability is necessary to capitalize on the technique in many envisioned applications. Here, we solve the problem and study the use of small metallic nanoparticles with an ellipsoidal shape as the material from which the shell is made to build an isotropic geometry. Changing the aspect ratio of the ellipsoids allows us to change the operational frequency. The basic functionality is explored with two complementary analytical approaches. Additionally, we present a powerful multiscattering algorithm that can be used to perform full-wave simulations of clusters of arbitrary particles. We utilize this method to analyze the scattering of the presented designs numerically. Herein we provide useful guidelines for the fabrication of this cloak with self-assembly methods by investigating the effects of disorder.
Time-of-flight imaging of invisibility cloaks
Halimeh, Jad C
2011-01-01
As invisibility cloaking has recently become experimental reality, it is interesting to explore ways to reveal remaining imperfections. In essence, the idea of most invisibility cloaks is to recover the optical path lengths without an object (to be made invisible) by a suitable arrangement around that object. Optical path length is proportional to the time of flight of a light ray or to the optical phase accumulated by a light wave. Thus, time-of-flight images provide a direct and intuitive tool for probing imperfections. Indeed, recent phase-sensitive experiments on the carpet cloak have already made early steps in this direction. In the macroscopic world, time-of-flight images could be measured directly by light detection and ranging (LIDAR). Here, we show calculated time-of-flight images of the conformal Gaussian carpet cloak, the conformal grating cloak, the cylindrical free-space cloak, and of the invisible sphere. All results are obtained by using a ray-velocity equation of motion derived from Fermat's ...
Dynamic Soil-Structure Interaction of Instrumented Buildings and Test Structures
Givens, Michael James
2013-01-01
The effects of soil-structure interaction (SSI) are investigated through careful interpretation of available data from instrumented buildings and recently performed forced vibration experiments on instrumented buildings and test structures. Conventional engineering practice typically ignores soil-structure interaction (SSI) during evaluation of the seismic demand on buildings based on the perception that consideration of SSI will reduce demands on structures and ignoring SSI effects will caus...
Strengthening of building structures using carbon composite materials
Directory of Open Access Journals (Sweden)
N.V. Paranicheva
2010-03-01
Full Text Available Currently, the question of ensuring the reliability of various building structures both at the stage of their construction and during operation is very urgent. There are a lot of different ways and constructive methods of structures strengthening. Аt the same time, traditional ways of concrete structures strengthening with steel reinforcement are such expensive, time consuming and in some cases require to interrupt the building operation. As an alternative, it is proposed to use composite materials based on high-strength carbon fibers.The authors consider the properties, advantages, disadvantages and the methods of application of these materials. This article presents results of a technical survey carried out in a public building in 2009. In this building the CFRP was used to strengthen concrete slabs, resting on the crossbar consoles. The calculation of the strength is adduced and the section selection is made. The authors demonstrate their conclusions about the feasibility of using carbon composite materials.
Structural Simulations and Conservation Analysis -Historic Building Information Model (HBIM
Directory of Open Access Journals (Sweden)
C. Dore
2015-02-01
Full Text Available In this paper the current findings to date of the Historic Building Information Model (HBIM of the Four Courts in Dublin are presented. The Historic Building Information Model (HBIM forms the basis for both structural and conservation analysis to measure the impact of war damage which still impacts on the building. The laser scan survey was carried out in the summer of 2014 of the internal and external structure. After registration and processing of the laser scan survey, the HBIM was created of the damaged section of the building and is presented as two separate workflows in this paper. The first is the model created from historic data, the second a procedural and segmented model developed from laser scan survey of the war damaged drum and dome. From both models structural damage and decay simulations will be developed for documentation and conservation analysis.
Soil Structure Interaction between Two Adjacent Buildings under Earthquake Load
Directory of Open Access Journals (Sweden)
Mahmoud Yahyai
2008-01-01
Full Text Available In some cases, tall buildings are located in geotechnically unsuitable places, due to their high ratio of height to width; there is risk of uplift and other effects such as overturning and reduction structure serviceability during earthquake. This research is aimed to evaluate the effect of Soil-Structure Interaction (SSI on seismic behavior of two adjacent 32 story buildings such as time period, base shear and displacements. The interaction effects are investigated for variable distance between the two buildings. Three types of soil such as soft clay, sandy gravel and compacted sandy gravel are considered for this study. The result obtained that the interaction effect increases time period of both buildings base shear and lateral displacement of the structures increases.
Behbahani, Mina Morshed; Amooghorban, Ehsan; Mahdifar, Ali
2016-01-01
As a probe to explore the ability of invisibility cloaks to conceal objects in the quantum mechanics domain, we study the spontaneous emission rate of an excited two-level atom in the vicinity of an ideal invisibility cloaking. On this base, first, a canonical quantization scheme is presented for the electromagnetic field interacting with atomic systems in an anisotropic, inhomogeneous and absorbing magnetodielectric medium which can suitably be used for studying the influence of arbitrary in...
Building damage due to structural pounding during earthquakes
Sołtysik, B.; Jankowski, R.
2015-07-01
Earthquake-induced pounding between adjacent buildings has been identified as one of the reasons for substantial damage or even total collapse of colliding structures. A major reason leading to interactions in buildings results from the differences in their dynamic parameters and also from insufficient distance between the structures. Although the research on structural pounding has been much advanced, the studies have mainly been conducted for concrete structures. The aim of this paper is to show the results of the non-linear numerical analysis focuses on damage due to pounding between two steel buildings under earthquake excitation. The numerical analysis has been performed using models of steel asymmetric structures with different number of storeys which makes them vibrate out-of-phase. Pounding between buildings has been controlled using three-dimensional gap-friction elements which become active when contact is detected. In order to identify the dynamic characteristics of analyzed structures, the modal analysis has been first conducted. Then, the detailed non-linear dynamic analysis of colliding structures has been performed. The acceleration time histories of the El Centro earthquake have been used in the numerical analysis. The results of the study clearly indicate that pounding may substantially influence the response of steel buildings intensifying their damage during earthquakes.
Folded Plate Structures as Building Envelopes
DEFF Research Database (Denmark)
Falk, Andreas; Buelow, Peter von; Kirkegaard, Poul Henning
This paper treats applications of cross-laminated timber (CLT) in structural systems for folded façade solutions. Previous work on CLT-based systems for folded roofs has shown a widening range of structural possibilities to develop timber-based shells. Geometric and material properties play...... CLT-based systems, which are studied and analysed by using a combination of digital tools for structural and environmental design and analysis. The results show gainful, rational properties of folded systems and beneficial effects from an integration of architectural and environmental performance...... criteria in the design of CLT-based façades....
Source amplitudes for active exterior cloaking
International Nuclear Information System (INIS)
The active cloak comprises a discrete set of multipole sources that destructively interfere with an incident time harmonic scalar wave to produce zero total field over a finite spatial region. For a given number of sources and their positions in two dimensions it is shown that the multipole amplitudes can be expressed as infinite sums of the coefficients of the incident wave decomposed into regular Bessel functions. The field generated by the active sources vanishes in the infinite region exterior to a set of circles defined by the relative positions of the sources. The results provide a direct solution to the inverse problem of determining the source amplitudes. They also define a broad class of non-radiating discrete sources. (paper)
Seismic soil-structure interaction in buildings. II: Empirical findings
Stewart, Jonathan P.; Seed, Raymond B; Fenves, Greggory L
1999-01-01
System identification analyses are used to evaluate soil-structure interaction effects for 77 strong motion data sets at 57 building sites that encompass a wide range of structural and geotechnical conditions. Kinematic interaction effects on the "input" motion at the bases of structures are found to be relatively modest in many cases, whereas inertial interaction effects on the structural response to these motions can be significant. To quantify inertial interaction effects, fixed- and flexi...
Invisibility Cloaks Modeled by Anisotropic Metamaterials Based on Inductor-capacitor Networks
Liu, Xiao; Li, Chao; Yao, Kan; Meng, Xiankun; Li, Fang
2009-01-01
Based on the transformation optics, a novel transmission-line (TL) approach to realize invisibility cloaking using planar anisotropic metamaterials (MTMs) is proposed. The two-dimensional cylindrical cloaks are modeled based on inductor-capacitor (L-C) MTMs networks. The three elements of the constitutive parameters are all allowed to be spatially inhomogeneous which lead to the full parameter realization of a cylindrical cloak. As an example, a cloak working at VHF band is modeled and its in...
Building nuclear structures : challenges and achievements
International Nuclear Information System (INIS)
Reliability and safety are factors of prime importance in construction of civil engineering structures of nuclear facilities. There cannot be any compromise in the strength and life of the structure. This involves rigorous control of: (1) quality of materials and end products, (2) time taken for construction, (3) cost, and also continuing innovation. India has now accumulated more than three decades of experience in nuclear civil engineering and the civil engineering fraternity of India and particularly of the Department of Atomic Energy is now fully capable of designing and construction of all types of structures involved in the nuclear field. Illustrative examples are given. Dome of the CIRUS reactor was constructed in steel plates, but then there was a switch over to reinforced concrete for containment structures and subsequently to prestressed concrete. The aspects taken into consideration of the design to ensure absolute leak tightness are: (1) earthquake safeguards, (2) concrete surface protection, and (3) minimization of cracking in concrete due to pressure loading and shrinkage. Coordination charts are prepared for monitoring time required for various operations and time and motion studies are employed to cut down on construction time. Close control over the cost is kept through internal and external audit, executing the work departmentally or employing an outside agency as the occasion demands and proper selection of materials. Some of the innovations in materials use and construction techniques are mentioned. (K.M.)
Electoral structure of building foundations in nuclear fuel element plant
International Nuclear Information System (INIS)
Plant structures of nuclear fuel elements have a substantial burden. This requires analysis of the selection of the proper foundation for building support for a variety of different soil conditions found in two locations, first at a location near the nuclear power plant in Jepara and the second location BATAN Serpong area. Expected to know the location of soil conditions, we can determined the type of foundation that will be used based on the criteria requirements of the building. (author)
Superlens-cloaking of small dielectric bodies in the quasistatic regime
Bruno, Oscar P.; Lintner, Stéphane
2007-01-01
It has been conjectured that, in the quasistatic regime, dielectric bodies of finite size could be perfectly cloaked by certain cylindrical arrangements of materials of positive and negative permittivities known as superlenses. We show that, although they do not cloak perfectly dielectrics objects of any size, cylindrical superlenses do cloak, to a significant extent, dielectric bodies of small size.
Smolyaninova, V. N.; Smolyaninov, I. I.; Ermer, H. K.
2012-01-01
Very recently Farhat et al. [1] have suggested that arrays of invisibility cloaks may find important applications in low-interference communication, noninvasive probing, sensing and communication networks, etc. We report on the first experimental realization of such an array of broadband invisibility cloaks, which operates in the visible frequency range. Wavelength and angular dependencies of the cloak array performance have been studied.
Structural Analysis of Buildings at Explosive Actions in SCAD
Directory of Open Access Journals (Sweden)
N.A. Chernukha
2014-02-01
Full Text Available This article deals with the methods of structural analysis of buildings and structures at explosive actions. In introduction, there is a review of types of explosions and the features of their action on structures. In the theoretical part of the study the main issue was to present different methods of structural analysis of buildings at explosions. Determination of wave parameters and process of wave diffraction are presented. Impulse loading of building structures in SCAD is described. The article also shows how module «Direct integration of motion equations» in SCAD can be used for solving problems of explosion dynamics. In the empirical part of the study the main concern was to compare stress-strain condition of building structures at explosions, using different methods of structural analysis. Automatic analysis was performed in SCAD, which implements finite element method (FEM. The results of the study demonstrate the advantages and disadvantages of described methods, as well as the functional abilities of SCAD, when solving the problems of explosion dynamics.
Seismic safety of building structures of NPP Kozloduy III
International Nuclear Information System (INIS)
In the proposed paper is presented a general summary of the analyses carried out to evaluate the dynamic behavior and to assess the seismic safety of some safety related building structures of NPP Kozloduy. The design seismic loads for the site of Kozloduy NPP has been reevaluated and increased during and after the construction of investigated Units 5 and 6. Deterministic and probabilistic approaches are applied to assess the seismic vulnerability of the investigated structures, taking into account the newly defined seismic excitations. The presented results show sufficient seismic safety for the studied critical structures and good efficiency of the seismic upgrading. The applicability of the investigated structures at sites with some higher seismic activities is discussed. The presented study is dealing mainly with the civil structures of the Reactor building, Turbine hall, Diesel Generator Station and Water Intake Structure. (authors)
Testing the technical condition of maintained building structures
A.A. Smorchkov; S.A. Kereb; Orlov, D. A.; K.O. Baranovskiy
2012-01-01
The accumulation of damage in structures under mechanical and environmental influences reduces their carrying capacity and changes its technical condition.A new approach to the evaluation of technical condition of building structures. Besides comparing the strength and deformation parameters it was proposed additional criteria: the probability of failure and reliability index. That allows setting the clear boundaries between categories of technical condition from the positions of structure in...
Hydraulic behaviour of a representative structural volume for containment buildings
Jason, L; Pijaudier-Cabot, Gilles; Ghavamian, S.; Huerta, Antonio
2007-01-01
For particular structures like containment buildings of nuclear power plants, the study of the hydraulic behaviour is of great concern. These structures are indeed the third barrier used to protect the environment in case of accidents. The evolution of the leaking rate through the porous medium is closely related to the changes in the permeability during the ageing process of the structure. It is thus essential to know the relation between concrete degradation and the transfer property when t...
International Nuclear Information System (INIS)
Replies are made to comments in N N Rozanov's letter to the editors ''Can even monochromatic radiation ensure ideal invisibility?'' (see Usp. Fiz. Nauk 181 787 (2011) [Phys. Usp. 54 763 (2011)]) concerning our paper ''Invisible cloaking of material bodies using the wave flow method'' (Usp. Fiz. Nauk 180 475 (2010) [Phys. Usp. 53 455 (2010)]). Examples are given of spatial configurations that enable the creation of singularity-free cloaking materials. Some emerging cloaking ideas are discussed. (letters to the editors)
Structural integrity analysis of an INPP building under external loading
International Nuclear Information System (INIS)
After the terrorist attacks in New York and Washington D. C. using civil airplanes, the evaluation of civil airplane crashes into civil and NPP structures has become very important. The interceptions of many terrorists' communications reveal that the use of commandeered commercial aircraft is still a major part of their plans for destruction. Aircraft crash or other flying objects in the territory of the Ignalina Nuclear Power Plant (INPP) represents a concern to the plant. Aircraft traveling at high velocity have a destructive potential. The aircraft crash may damage the roof and walls of buildings, pipelines, electric motors, cases of power supplies, power cables of electricity transmission and other elements and systems, which are important for safety. Therefore, the evaluation of the structural response to an of aircraft crash is important and was selected for analysis. The structural integrity analysis due to the effects of an aircraft crash on an NPP building structure is the subject of this paper. The finite element method was used for the structural analysis of a typical Ignalina NPP building. The structural integrity analysis was performed for a portion of the ALS using the dynamic loading of an aircraft crash impact model. The computer code NEPTUNE was used for this analysis. The local effects caused by impact of the aircraft's engine on the building wall were evaluated independently by using an empirical formula. (authors)
Phonons as building blocks in nuclear structure
International Nuclear Information System (INIS)
The structure of a nuclear system in terms of eigenmodes (phonons) of subsystems is investigated in three different approaches. In the frame of nuclear field theory the three identical particle system is analysed and the elimination of spurious states due to the violation of the Pauli principle is emphasized. In terms of weak coupling, a new approach of the shell model is proposed which is shown to be rapidly convergent with the number of basis vectors. Applications of three particle systems in the lead region are made. Lastly, a microscopic multiphonon theorie of collective K=0 states in deformed nuclei based on a Tamm Dancoff phonon is developed. The role of the Pauli principle as well as comparisons with boson expansion methods are deeply analysed
ICT technologies for the refurbishment of wooden structure buildings
Arakistain, Ivan; Abascal, Jose Miguel; Munne, Oriol
2014-01-01
Nowadays, one would think that after years of massive concrete and steel construction in Spain, there are not many wood structure buildings left to be refurbished except for some palaces or cathedrals. However, if we go for a walk and have a look at the old part of any city, we will realize that still most of the buildings have a wood structure. In spite of the fact that the majority of urban regulations forbid their demolition, other bad practices such as casting and overloading the wood str...
Analysis of the structural design process of the adaptive reuse of building structures
Pasterkamp, S.
2014-01-01
In the field of structural building engineering there is a market shift taking place as a result of the growing number of buildings that are listed as cultural heritage, secularization, the economic situation and the increasing office vacancy rate in Europe and the US. More and more structural engin
Shen, Huijie; Wen, Jihong; Païdoussis, Michael P.; Yu, Dianlong; Cai, Li; Wen, Xisen
2013-09-01
This work derives the set of acoustic parameters of a metamaterial for an ideal cylindrical cloak through scattering theory. A multilayered cloak with homogeneous isotropic materials is introduced to approximate the ideal cloak. An active metamaterial, consisting of active arrays of acoustic cavities separated by piezo-diaphragms, is addressed to achieve the required parameters for each layer of the multilayered cloak. In particular, with the aid of a multi-control strategy that takes into account the coupling between adjacent cells, the effective parameters for the cloak can be accurately realized.
International Nuclear Information System (INIS)
By means of embedded optical transformation, three-dimensional diamond-shaped invisible cloaks composed of tetrahedral homogeneous blocks have been designed in this paper. The constitutive parameters of the invisible cloaks can be obtained based on the form invariance of Maxwell's equations in coordinate transformation. Numerical methods using the finite element method verified the diamond-shaped cloaks. The invisible properties of the designed cloaks are nearly perfect when the original line section is sufficiently short compared with its counterpart in the after-transformed space. The designed cloaks can operate in a wide bandwidth due to the line transformation in the coordinate transformation process.
Invisible anti-cloak with elliptic cross section using phase complement
International Nuclear Information System (INIS)
Based on the theory of phase complement, an anti-cloak with circular cross section can be made invisible to an object outside its domain. As the cloak with elliptic cross section is more effective to make objects invisible than that with circular cross section, a scaled coordinate system is proposed to design equivalent materials of invisible anti-cloak with elliptic cross section using phase complement. The cloaks with conventional dielectric and double negative parameters are both simulated with the geometrical transformations. The results show that the cloak with elliptic cross section through phase complement can effectively hide the outside objects. (classical areas of phenomenology)
Confirmation of Cylindrical Perfect Invisibility Cloak Using Fourier-Bessel Analysis
Ruan, Zhichao; Yan, Min; Neff, Curtis W.; Qiu, Min
2007-01-01
A cylindrical wave expansion method is developed to obtain the scattering field for an ideal two-dimensional cylindrical invisibility cloak. A near-ideal model of the invisibility cloak is set up to solve the boundary problem at the inner boundary of the cloak shell. We confirm that a cloak with the ideal material parameters is a perfect invisibility cloak by systematically studying the change of the scattering coefficients from the near-ideal case to the ideal one. However, due to the slow c...
International Nuclear Information System (INIS)
This work derives the set of acoustic parameters of a metamaterial for an ideal cylindrical cloak through scattering theory. A multilayered cloak with homogeneous isotropic materials is introduced to approximate the ideal cloak. An active metamaterial, consisting of active arrays of acoustic cavities separated by piezo-diaphragms, is addressed to achieve the required parameters for each layer of the multilayered cloak. In particular, with the aid of a multi-control strategy that takes into account the coupling between adjacent cells, the effective parameters for the cloak can be accurately realized. (paper)
The relation between ventilation rates and building structures
International Nuclear Information System (INIS)
As the concept of building and structure includes so various kinds of factors, the discussion in this paper on the ventilation rates refers mainly to the 'residential buildings' of 'reinforced concrete and timber frame'. Although it was believed, since before the world war II, that the concrete structure was better in air tightness than the timber frame of which ventilation rates were estimated as more than one air change per hour or so, it is getting hard to decide which one is tighter and to estimate the amount of ventilation rate based on just only the construction style. A description was given on the methodology to estimate the ventilation rate of a house using a simple chart. Outline of the values thus obtained is presented for the ventilation rates in Japanese residential buildings. (author)
Structural approach for building reconstruction from a single DSM.
Lafarge, Florent; Descombes, Xavier; Zerubia, Josiane; Pierrot-Deseilligny, Marc
2010-01-01
We present a new approach for building reconstruction from a single Digital Surface Model (DSM). It treats buildings as an assemblage of simple urban structures extracted from a library of 3D parametric blocks (like a LEGO set). First, the 2D-supports of the urban structures are extracted either interactively or automatically. Then, 3D-blocks are placed on the 2D-supports using a Gibbs model which controls both the block assemblage and the fitting to data. A Bayesian decision finds the optimal configuration of 3D-blocks using a Markov Chain Monte Carlo sampler associated with original proposition kernels. This method has been validated on multiple data set in a wide-resolution interval such as 0.7 m satellite and 0.1 m aerial DSMs, and provides 3D representations on complex buildings and dense urban areas with various levels of detail. PMID:19926904
GLLH EM Invisible Cloak With Novel Front Branching And Without Exceed Light Speed Violation
Xie, Ganquan; Xie, Lee; Xie, Feng
2010-01-01
In this paper, we propose new Global and Local (GL) electromagnetic (EM) cloaks with distinctive class material a_{\\alpha \\beta}\\log ^\\alpha (b_{\\alpha \\beta}/h) h^\\beta (GLLH Cloak) without exceed light speed violation. The refractive index of the GLLH cloak material, $n(r)$, is large than one or equal to one. Our GLLH cloak is created by GL EM modeling and GL EM cloak inversion with searching class \\it a_{\\alpha \\beta}\\log ^\\alpha (b_{\\alpha \\beta}/h) h^\\beta. The GLLH cloaks in this paper have finite speed and have no exceed light speed? physical violations and have more advantages. The GLLH EM cloaks can be practicable by using normal materials and are available for all broad frequency band. The GL EM cloak inversion and electromagnetic integral equation for cloak are presented in this paper. The novel EM wave propagation and front branching in the GLLH cloak by GL EM modeling are presented in this paper. The EM wave front propagation in GLLH cloak is behind of the front in free space. At time steps $118 ...
A metasurface carpet cloak for electromagnetic, acoustic and water waves
Yang, Yihao; Wang, Huaping; Yu, Faxin; Xu, Zhiwei; Chen, Hongsheng
2016-01-01
We propose a single low-profile skin metasurface carpet cloak to hide objects with arbitrary shape and size under three different waves, i.e., electromagnetic (EM) waves, acoustic waves and water waves. We first present a metasurface which can control the local reflection phase of these three waves. By taking advantage of this metasurface, we then design a metasurface carpet cloak which provides an additional phase to compensate the phase distortion introduced by a bump, thus restoring the reflection waves as if the incident waves impinge onto a flat mirror. The finite element simulation results demonstrate that an object can be hidden under these three kinds of waves with a single metasurface cloak.
Ultrathin skin cloaks with metasurfaces for audible sound
Zhai, Shilong; Chen, Huaijun; Ding, Changlin; Li, Linlin; Shen, Fangliang; Luo, Chunrong; Zhao, Xiaopeng
2016-06-01
We report a design of 2D acoustic skin cloaks by using ultrathin metasurfaces in audible range. The microunit of this metasurface is constructed by a cavity coupled with a membrane. This cloak can completely compensate the wave front discrepancy generated by the scattering of the hidden object because the microunits are capable of arbitrarily modulating the reflected amplitude and phase. The operating frequency ranges from 3.54 kHz to 3.93 kHz. The tolerated maximum incident angle decreases as the height of the hidden object increases. Moreover, the cloak’s thickness is only approximately λ/10, so that we can make an object in almost any shape undetectable without obviously increasing the size of the whole system. This intriguing feature forms a sharp contrast to most bulky cloaks on the basis of coordination transformations.
Nonlinear pre-stress for cloaking from antiplane elastic waves
Parnell, William J
2012-01-01
A theory is presented showing that cloaking of objects from antiplane elastic waves can be achieved by elastic pre-stress of a neo-Hookean nonlinear elastic material. This approach would appear to eliminate the requirement of metamaterials with inhomogeneous anisotropic shear moduli and density. Waves in the pre-stressed medium are bent around the cloaked region by inducing inhomogeneous stress fields via pre-stress. The equation governing antiplane waves in the pre-stressed medium is equivalent to the antiplane equation in an unstressed medium with inhomogeneous and anisotropic shear modulus and isotropic scalar mass density. Note however that these properties are induced naturally by the pre-stress. Since the magnitude of pre-stress can be altered at will, this enables objects of varying size and shape to be cloaked by placing them inside the fluid-filled deformed cavity region.
Mantle cloaking for co-site radio-frequency antennas
Monti, Alessio; Soric, Jason; Barbuto, Mirko; Ramaccia, Davide; Vellucci, Stefano; Trotta, Fabrizio; Alù, Andrea; Toscano, Alessandro; Bilotti, Filiberto
2016-03-01
We show that properly designed mantle cloaks, consisting of patterned metallic sheets placed around cylindrical monopoles, allow tightly packing the same antennas together in a highly dense telecommunication platform. Our experimental demonstration is applied to the relevant example of two cylindrical monopole radiators operating for 3G and 4G mobile communications. The two antennas are placed in close proximity, separated by 1/10 of the shorter operational wavelength, and, after cloaking, are shown to remarkably operate as if isolated in free-space. This result paves the way to unprecedented co-siting strategies for multiple antennas handling different services and installed in overcrowded platforms, such as communication towers, satellite payloads, aircrafts, or ship trees. More broadly, this work presents a significant application of cloaking technology to improve the efficiency of modern communication systems.
Structural response of steel high rise buildings to fire
DEFF Research Database (Denmark)
Gentili, Filippo; Giuliani, Luisa; Bontempi, Franco
2013-01-01
fire is also very important. In this context, it is of interest to investigate the characteristics of the structural system that could possibly reduce local damages or mitigate the progression of failures in case of fire. In this paper, a steel high rise building is taken as case study and the response...
Single frequency microwave cloaking and subwavelength imaging with curved wired media.
Ktorza, Ilan; Ceresoli, Lauris; Enoch, Stefan; Guenneau, Sébastien; Abdeddaim, Redha
2015-04-20
We consider the cloaking properties of electromagnetic wired media deduced from arbitrary coordinate transformations. We propose an interpretation of invisibility via sub-wavelength imaging features. The quality of cloaking is assessed by the level of deformation of the image of a P-shaped source through the stretched wired media: the lesser the image deformation, the more effective the cloaking. We numerically and experimentally demonstrate a tetrahedral wired cloak with longer edge length about 7cm at a frequency of 1GHz (the cloak is thus subwavelength). The wired cloak has two functionalities: it can serve as a high-resolution imaging system over long distances, and it can also perform space transformations such as, but not limited to, cloaking at a single operation frequency. PMID:25969073
Optical force on a discrete invisibility cloak in time-dependent fields
Energy Technology Data Exchange (ETDEWEB)
Chaumet, Patrick C.; Zolla, Frederic; Nicolet, Andre; Belkebir, Kamal [Institut Fresnel, CNRS, Aix-Marseille Universite, Campus de St-Jerome 13013 Marseille (France); Rahmani, Adel [Department of Mathematical Sciences, University of Technology, Sydney, Broadway NSW 2007 (Australia)
2011-09-15
We study, in time domain, the exchange of momentum between an electromagnetic pulse and a three-dimensional, discrete, spherical invisibility cloak. We find that a discrete cloak, initially at rest, would experience an electromagnetic force due to the pulse but would acquire zero net momentum and net displacement. On the other hand, we find that while the cloak may manage to conceal an object and shroud it from the electromagnetic forces associated with the pulse, the cloak itself can experience optomechanical stress on a scale much larger than the object would in the absence of the cloak. We also consider the effects of material dispersion and losses on the electromagnetic forces experienced by the cloak and show that they lead to a transfer of momentum from the pulse to the cloak.
Optical force on a discrete invisibility cloak in time-dependent fields
International Nuclear Information System (INIS)
We study, in time domain, the exchange of momentum between an electromagnetic pulse and a three-dimensional, discrete, spherical invisibility cloak. We find that a discrete cloak, initially at rest, would experience an electromagnetic force due to the pulse but would acquire zero net momentum and net displacement. On the other hand, we find that while the cloak may manage to conceal an object and shroud it from the electromagnetic forces associated with the pulse, the cloak itself can experience optomechanical stress on a scale much larger than the object would in the absence of the cloak. We also consider the effects of material dispersion and losses on the electromagnetic forces experienced by the cloak and show that they lead to a transfer of momentum from the pulse to the cloak.
A unidirectional acoustic cloak for multilayered background media with homogeneous metamaterials
Zhu, Jian; Chen, Tianning; Liang, Qingxuan; Wang, Xiaopeng; Xiong, Jie; Jiang, Ping
2015-08-01
The acoustic cloak, which can make an object hard to detect acoustically in a homogeneous background, has attracted great attention from researchers in recent years. The inhomogeneous background media were considered in this paper. The relative constitutive parameters were derived for acoustic cloaks working in multilayered media. And a unidirectional acoustic cloak for layered background media was proposed, designed and implemented successfully in a wide frequency range. In water and NaCl aqueous solution, the acoustic cloak was designed and realized with homogeneous metamaterials which were composed of steel and porous materials. The effective parameters of the unit cells of the cloak were determined by using the effective medium theory. Numerical results demonstrated excellent cloaking performance and showed that such a device could be physically realized with natural materials which will greatly promote the real applications of an invisibility cloak in inhomogeneous backgrounds.
A unidirectional acoustic cloak for multilayered background media with homogeneous metamaterials
International Nuclear Information System (INIS)
The acoustic cloak, which can make an object hard to detect acoustically in a homogeneous background, has attracted great attention from researchers in recent years. The inhomogeneous background media were considered in this paper. The relative constitutive parameters were derived for acoustic cloaks working in multilayered media. And a unidirectional acoustic cloak for layered background media was proposed, designed and implemented successfully in a wide frequency range. In water and NaCl aqueous solution, the acoustic cloak was designed and realized with homogeneous metamaterials which were composed of steel and porous materials. The effective parameters of the unit cells of the cloak were determined by using the effective medium theory. Numerical results demonstrated excellent cloaking performance and showed that such a device could be physically realized with natural materials which will greatly promote the real applications of an invisibility cloak in inhomogeneous backgrounds. (paper)
Ammari, Habib; Ciraolo, Giulio; Kang, Hyeonbae; Lee, Hyundae; Milton, Graeme W.
2013-01-01
The aim of this paper is to give a mathematical justification of cloaking due to anomalous localized resonance (CALR). We consider the dielectric problem with a source term in a structure with a layer of plasmonic material. Using layer potentials and symmetrization techniques, we give a necessary and sufficient condition on the fixed source term for electromagnetic power dissipation to blow up as the loss parameter of the plasmonic material goes to zero. This condition is written in terms of ...
Dynamic soil-structure interactions on embedded buildings
International Nuclear Information System (INIS)
The dynamic soil-structure interaction on the horizontal seismic excitation is investigated on two typical embedded auxiliary buildings of a nuclear power plant. The structure and the soil are modelled by various analytical and numerical methods. Under the condition of the linear viscoelastic theory, i.e. soil characteristic constant in time and independent of strain, the interaction influences between a homogenous soil layer and a structure are analysied for the following parameters: 4) mathematical soil modells; 4) mathematical structure modells; 4) shear wave velocities; 3) embedment conditions; 4) earthquake time histories. (orig.)
Detection of a diffusive cloak via second-order statistics
Koirala, Milan
2016-01-01
We propose a scheme to detect the diffusive cloak proposed by Schittny et al [Science 345, 427 (2014)]. We exploit the fact that diffusion of light is an approximation that disregards wave interference. The long-range contribution to intensity correlation is sensitive to locations of paths crossings and the interference inside the medium, allowing one to detect the size and position, including the depth, of the diffusive cloak. Our results also suggest that it is possible to separately manipulate the first- and the second-order statistics of wave propagation in turbid media.
Thermal invisibility based on scattering cancellation and mantle cloaking.
Farhat, M; Chen, P-Y; Bagci, H; Amra, C; Guenneau, S; Alù, A
2015-01-01
We theoretically and numerically analyze thermal invisibility based on the concept of scattering cancellation and mantle cloaking. We show that a small object can be made completely invisible to heat diffusion waves, by tailoring the heat conductivity of the spherical shell enclosing the object. This means that the thermal scattering from the object is suppressed, and the heat flow outside the object and the cloak made of these spherical shells behaves as if the object is not present. Thermal invisibility may open new vistas in hiding hot spots in infrared thermography, military furtivity, and electronics heating reduction. PMID:25928664
Thermal invisibility based on scattering cancellation and mantle cloaking
Farhat, M.
2015-04-30
We theoretically and numerically analyze thermal invisibility based on the concept of scattering cancellation and mantle cloaking. We show that a small object can be made completely invisible to heat diffusion waves, by tailoring the heat conductivity of the spherical shell enclosing the object. This means that the thermal scattering from the object is suppressed, and the heat flow outside the object and the cloak made of these spherical shells behaves as if the object is not present. Thermal invisibility may open new vistas in hiding hot spots in infrared thermography, military furtivity, and electronics heating reduction.
Models test on dynamic structure-structure interaction of nuclear power plant buildings
International Nuclear Information System (INIS)
A reactor building of an NPP (nuclear power plant) is generally constructed closely adjacent to a turbine building and other buildings such as the auxiliary building, and in increasing numbers of NPPs, multiple plants are being planned and constructed closely on a single site. In these situations, adjacent buildings are considered to influence each other through the soil during earthquakes and to exhibit dynamic behaviour different from that of separate buildings, because those buildings in NPP are generally heavy and massive. The dynamic interaction between buildings during earthquake through the soil is termed here as 'dynamic cross interaction (DCI)'. In order to comprehend DCI appropriately, forced vibration tests and earthquake observation are needed using closely constructed building models. Standing on this background, Nuclear Power Engineering Corporation (NUPEC) had planned the project to investigate the DCI effect in 1993 after the preceding SSI (soil-structure interaction) investigation project, 'model tests on embedment effect of reactor building'. The project consists of field and laboratory tests. The field test is being carried out using three different building construction conditions, e.g. a single reactor building to be used for the comparison purposes as for a reference, two same reactor buildings used to evaluate pure DCI effects, and two different buildings, reactor and turbine building models to evaluate DCI effects under the actual plant conditions. Forced vibration tests and earthquake observations are planned in the field test. The laboratory test is planned to evaluate basic characteristics of the DCI effects using simple soil model made of silicon rubber and structure models made of aluminum. In this test, forced vibration tests and shaking table tests are planned. The project was started in April 1994 and will be completed in March 2002. This paper describes an outline and the summary of the current status of this project. (orig.)
Minimization of structure-borne noise in lightweight buildings
DEFF Research Database (Denmark)
Niu, Bin; Olhoff, Niels
2012-01-01
This paper deals with the problem of minimizing the structure-borne noise induced in a room by machinery vibration. A generalized system consisting of the machine, the base plate, resilient mounts, the floor plate and the room cavity is developed for analysis and optimization. Topological design of...... the base plate is studied for optimizing machinery installation. Furthermore, periodic mounts are optimized for the noise reduction. Finally, a modular model of a lightweight building is developed for design optimization of dimensions and connections of modules in the building for decreasing machinery...... vibration transmission....
Behbahani, Mina Morshed; Mahdifar, Ali
2016-01-01
As a probe to explore the ability of invisibility cloaks to conceal objects in the quantum mechanics domain, we study the spontaneous emission rate of an excited two-level atom in the vicinity of an ideal invisibility cloaking. On this base, first, a canonical quantization scheme is presented for the electromagnetic field interacting with atomic systems in an anisotropic, inhomogeneous and absorbing magnetodielectric medium which can suitably be used for studying the influence of arbitrary invisibility cloak on the atomic radiative properties. The time dependence of the atomic subsystem is obtained in the Schrodinger picture. By introducing a modified set of the spherical wave vector functions, the Green tensor of the system is calculated via the continuous and discrete methods. In this formalism, the decay rate and as well the emission pattern of the aforementioned atom are computed analytically for both weak and strong coupling interaction, and then numerically calculations are done to demonstrate the perfo...
Special tests of building structures of Dukovany nuclear power plant
International Nuclear Information System (INIS)
Two demanding safety tests for leaks are described applied to building structures of the Dukovany nuclear power plant. A hydrostatic leak test was conducted of tanks permanently or temporarily flooded, and an integral leak test was performed of the power plant sealed space. The objective was to show that the structures are leakproof in case of a hypothetical accident of the production unit. The hydrostatic leak test was performed by flooding the central part with 500 m3 of demineralized water. For the integral leak test the sealed space was pressurized with air to a value of 144 kPa. Defects inside the sealed space were continuously detected and removed. The lose of air in 24 hours was calculated. It is recommended that the experience gained should be used to work out standard requirements on leak tests of building structures of nuclear power plants. (Pu)
Prediction of Noise Transmission in Lightweight Building Structures
DEFF Research Database (Denmark)
Dickow, Kristoffer Ahrens
tool to predict the flanking transmission of air-borne and structure borne sound already at the design stage. However, lightweight building structures typically do not meet the requirements for ideal SEA subsystems and, therefore, applying the EN 12354 standard to lightweight building structures may...... paper about the modal density of ribbed plates at mid/high frequencies is presented. The modal density in such plates is not a uniform distribution, but instead it undergoes an undulating behavior with corresponding pass bands and stop bands. It is demonstrated, how the modes can be divided in two...... groups, where one group shows pass band/stop band behavior, while the other has a nearly uniform distribution of modes. The suggested approach for SEA adaptation is to consider a ribbed plate as two SEA subsystems: One that contains modes related to waves traveling in the direction orthogonal to the ribs...
Structural design of SBWR reactor building complex using microcomputers
International Nuclear Information System (INIS)
The design concept of Simplified Boiling Water Reactor (SBWR) plant is based on simplicity and passive features to enhance safety and reliability, improve performance, and increase economic viability. The SBWR utilizes passive systems such as Gravity Driven Core-Cooling System (GDCS) and Passive Containment Cooling System (PCCS). To suit these design features the Reactor Building (RB) complex of the SBWR is configured as an integrated structure consisting of a cylindrical Reinforced Concrete Containment Vessel (RCCV) surrounded by square reinforced concrete safety envelope and outer box structures, all sharing a common reinforced concrete basemat. This paper describes the structural analysis and design aspects of the RB complex. A 3D STARDYNE finite element model has been developed for the structural analysis of the complex using a PC Compaq 486/33L microcomputer. The structural analysis is performed for service and factored load conditions for the applicable loading combinations. The dynamic responses of containment structures due to pool hydrodynamic loads have been calculated by an axisymmetric shell model using COSMOS/M program. The RCCV is designed in accordance with ASME Section 3, Division 2 Code. The rest of the RB which is classified as Seismic Category 1 structure is designed in accordance with the ACI 349 Code. This paper shows that microcomputers can be efficiently used for the analysis and design of large and complex structures such as RCCV and Reactor Building complex. The use of microcomputers can result in significant savings in the computational cost compared with that of mainframe computers
Testing the technical condition of maintained building structures
Directory of Open Access Journals (Sweden)
A.A. Smorchkov
2012-11-01
Full Text Available The accumulation of damage in structures under mechanical and environmental influences reduces their carrying capacity and changes its technical condition.A new approach to the evaluation of technical condition of building structures. Besides comparing the strength and deformation parameters it was proposed additional criteria: the probability of failure and reliability index. That allows setting the clear boundaries between categories of technical condition from the positions of structure indestructibility.The example of using the proposed method in practice was given in the article.
Schroeder, Aaron David
2001-01-01
The purpose of this dissertation is the delineation of a new approach, or, more precisely, a new â roleâ and â methodological system,â for those persons engaged in building and managing multi-actor structures, or â networks,â for the purpose of policy implementation. As policy formulation and implementation can be viewed increasingly as taking place inter-organizationally, and consisting of individuals, special-interest groups, public organizations, private organizations, non-profits...
Direct Georeferencing of Uav Data Based on Simple Building Structures
Tampubolon, W.; Reinhardt, W.
2016-06-01
Unmanned Aerial Vehicle (UAV) data acquisition is more flexible compared with the more complex traditional airborne data acquisition. This advantage puts UAV platforms in a position as an alternative acquisition method in many applications including Large Scale Topographical Mapping (LSTM). LSTM, i.e. larger or equal than 1:10.000 map scale, is one of a number of prominent priority tasks to be solved in an accelerated way especially in third world developing countries such as Indonesia. As one component of fundamental geospatial data sets, large scale topographical maps are mandatory in order to enable detailed spatial planning. However, the accuracy of the products derived from the UAV data are normally not sufficient for LSTM as it needs robust georeferencing, which requires additional costly efforts such as the incorporation of sophisticated GPS Inertial Navigation System (INS) or Inertial Measurement Unit (IMU) on the platform and/or Ground Control Point (GCP) data on the ground. To reduce the costs and the weight on the UAV alternative solutions have to be found. This paper outlines a direct georeferencing method of UAV data by providing image orientation parameters derived from simple building structures and presents results of an investigation on the achievable results in a LSTM application. In this case, the image orientation determination has been performed through sequential images without any input from INS/IMU equipment. The simple building structures play a significant role in such a way that geometrical characteristics have been considered. Some instances are the orthogonality of the building's wall/rooftop and the local knowledge of the building orientation in the field. In addition, we want to include the Structure from Motion (SfM) approach in order to reduce the number of required GCPs especially for the absolute orientation purpose. The SfM technique applied to the UAV data and simple building structures additionally presents an effective tool
Graphene based metamaterials for terahertz cloaking and subwavelength imaging
Forouzmand, Seyedali
Graphene is a two-dimensional carbon crystal that became one of the most controversial topics of research in the last few years. The intense interest in graphene stems from recent demonstrations of their potentially revolutionary electromagnetic applications -- including negative refraction, subdiffraction imaging, and even invisibility -- which have suggested a wide range of new devices for communications, sensing, and biomedicine. In addition, it has been shown that graphene is amenable to unique patterning schemes such as cutting, bending, folding, and fusion that are predicted to lead to interesting properties. A recent proposed application of graphene is in engineering the scattering properties of objects, which may be leveraged in applications such as radar-cross-section management and stealth, where it may be required to make one object look like another object or render an object completely invisible. We present the analytical formulation for the analysis of electromagnetic interaction with a finite conducting wedge covered with a cylindrically shaped nanostructured graphene metasurface, resulting in the scattering cancellation of the dominant scattering mode for all the incident and all the observation angles. Following this idea, the cylindrical graphene metasurface is utilized for cloaking of several concentric finite conducting wedges. In addition, a wedge shaped metasurface is proposed as an alternative approach for cloaking of finite wedges. The resolution of the conventional imaging lenses is restricted by the natural diffraction limit. Artificially engineered metamaterials now offer the possibility of creating a superlens that overcomes this restriction. We demonstrate that a wire medium (WM) slab loaded with graphene sheets enables the enhancement of the near field for subwavelength imaging at terahertz (THz) frequencies. The analysis is based on the nonlocal homogenization model for WM with the additional boundary condition in the connection of
Structural Analysis and Seismic Design for Cold Neutron Laboratory Building
International Nuclear Information System (INIS)
This report describes all the major results of the dynamic structural analysis and seismic design for the Cold Neutron Laboratory Building which is classified in seismic class II. The results are summarized of the ground response spectrum as seismic input loads, mechanical properties of subsoil, the buoyancy stability due to ground water, the maximum displacement of the main frame under the seismic load and the member design. This report will be used as a basic design report to maintenance its structural integrity in future
International Nuclear Information System (INIS)
An improved understanding of the factors that control radon entry into buildings is needed in order to reduce the public health risks caused by exposure to indoor radon. This dissertation examines three issues associated with radon entry into buildings: (1) the influence of a subslab gravel layer and the size of the openings between the soil and the building interior on radon entry; (2) the effect of atmospheric pressure fluctuations on radon entry; and (3) the development and validation of mathematical models which simulate radon and soil-gas entry into houses. Experiments were conducted using two experimental basements to examine the influence of a subslab gravel layer on advective radon entry driven by steady indoor-outdoor pressure differences. These basement structures are identical except that in one the floor slab lies directly on native soil whereas in the other the slab lies on a high-permeability gravel layer. The measurements indicate that a high permeability subslab gravel layer increases the advective radon entry rate into the structure by as much as a factor of 30. The magnitude of the enhancement caused by the subslab gravel layer depends on the area of the openings in the structure floor; the smaller the area of these openings the larger the enhancement in the radon entry rate caused by the subslab gravel layer. A three-dimensional, finite-difference model correctly predicts the effect of a subslab gravel layer and open area configuration on advective radon entry driven by steady indoor-outdoor pressure differences; however, the model underpredicts the absolute entry rate into each structure by a factor of 1.5
DIRECT GEOREFERENCING OF UAV DATA BASED ON SIMPLE BUILDING STRUCTURES
Directory of Open Access Journals (Sweden)
W. Tampubolon
2016-06-01
Full Text Available Unmanned Aerial Vehicle (UAV data acquisition is more flexible compared with the more complex traditional airborne data acquisition. This advantage puts UAV platforms in a position as an alternative acquisition method in many applications including Large Scale Topographical Mapping (LSTM. LSTM, i.e. larger or equal than 1:10.000 map scale, is one of a number of prominent priority tasks to be solved in an accelerated way especially in third world developing countries such as Indonesia. As one component of fundamental geospatial data sets, large scale topographical maps are mandatory in order to enable detailed spatial planning. However, the accuracy of the products derived from the UAV data are normally not sufficient for LSTM as it needs robust georeferencing, which requires additional costly efforts such as the incorporation of sophisticated GPS Inertial Navigation System (INS or Inertial Measurement Unit (IMU on the platform and/or Ground Control Point (GCP data on the ground. To reduce the costs and the weight on the UAV alternative solutions have to be found. This paper outlines a direct georeferencing method of UAV data by providing image orientation parameters derived from simple building structures and presents results of an investigation on the achievable results in a LSTM application. In this case, the image orientation determination has been performed through sequential images without any input from INS/IMU equipment. The simple building structures play a significant role in such a way that geometrical characteristics have been considered. Some instances are the orthogonality of the building’s wall/rooftop and the local knowledge of the building orientation in the field. In addition, we want to include the Structure from Motion (SfM approach in order to reduce the number of required GCPs especially for the absolute orientation purpose. The SfM technique applied to the UAV data and simple building structures additionally presents an
Seavy, Ryan
2014-01-01
Building for concrete is temporary. The building of wood and steel stands against the concrete to give form and then gives way, leaving a trace of its existence behind. Concrete is not a building material. One does not build with concrete. One builds for concrete.
Photorealistic ray tracing of free-space invisibility cloaks made of uniaxial dielectrics
Halimeh, Jad C
2012-01-01
The design rules of transformation optics generally lead to spatially inhomogeneous and anisotropic impedance-matched magneto-dielectric material distributions for, e.g., free-space invisibility cloaks. Recently, simplified anisotropic non-magnetic free-space cloaks made of a locally uniaxial dielectric material (calcite) have been realized experimentally. In a two-dimensional setting and for in-plane polarized light propagating in this plane, the cloaking performance can still be perfect for light rays. However, for general views in three dimensions, various imperfections are expected. In this paper, we study two different purely dielectric uniaxial cylindrical free-space cloaks. For one, the optic axis is along the radial direction, for the other one it is along the azimuthal direction. The azimuthal uniaxial cloak has not been suggested previously to the best of our knowledge. We visualize the cloaking performance of both by calculating photorealistic images rendered by ray tracing. Following and complemen...
A class of line-transformed cloaks with easily-realizable constitutive parameters
Jiang, Wei Xiang; Cheng, Qiang; Cui, Tie Jun
2009-01-01
We propose a class of line-transformed cylindrical cloaks which have easily-realizable constitutive parameters. The scattering properties of such cloaks have been investigated numerically for both transverse-electric (TE) and transverse-magnetic (TM) incidences of plane waves. A line-transformed invisibility cloak with a perfectly electric conducting (PEC) inner boundary is actually a reshaping of a PEC line to which the cloaked object is crushed. The numerical results of near-field distributions and far-field scattering properties have verified the above conclusions. We also investigate the relationship between the constitutive parameters of a line-transformed cloak and the length of the corresponding line. The changing range of constitutive parameters is large when the line is short, while the changing range becomes small when the line is long. The above conclusion provides an efficient way to realize the invisibility cloaks using artificial metamaterials.
Li, Chao; Yao, Kan; Li, Fang
2009-06-01
Transformation optics offers remarkable control over electromagnetic fields and opens an exciting gateway to design 'invisible cloak devices' recently. We present an important class of two-dimensional (2D) cloaks with polygon geometries. Explicit expressions of transformed medium parameters are derived with their unique properties investigated. It is found that the elements of diagonalized permittivity tensors are always positive within an irregular polygon cloak besides one element diverges to plus infinity and the other two become zero at the inner boundary. At most positions, the principle axes of permittivity tensors do not align with position vectors. An irregular polygon cloak is designed and its invisibility to external electromagnetic waves is numerically verified. Since polygon cloaks can be tailored to resemble any objects, the transformation is finally generalized to the realization of 2D cloaks with arbitrary geometries.
A 3D tunable and multi-frequency graphene plasmonic cloak
Farhat, Mohamed Dhia Eddine
2013-01-01
We demonstrate the possibility of cloaking three-dimensional objects at multi-frequencies in the far-infrared part of the spectrum. The proposed cloaking mechanism exploits graphene layers wrapped around the object to be concealed. Graphene layers are doped via a variable external voltage difference permitting continuous tuning of the cloaking frequencies. Particularly, two configurations are investigated: (i) Only one graphene layer is used to suppress the scattering from a dielectric sphere. (ii) Several of these layers biased at different gate voltages are used to achieve a multi-frequency cloak. These frequencies can be set independently. The proposed cloak\\'s functionality is verified by near- and far-field computations. By considering geometry and material parameters that are realizable by practical experiments, we contribute to the development of graphene based plasmonic applications that may find use in disruptive photonic technologies. © 2013 Optical Society of America.
Kamaruzzaman, Syahrul Nizam; Egbu, C O; Zawawi, Emma Marinie Ahmad; Karim, Saipol Bari Abd; Woon, Chen Jia
2015-05-01
It is accepted that occupants who are more satisfied with their workplace's building internal environment are more productive. The main objective of the study was to measure the occupants' level of satisfaction and the perceived importance of the design or refurbishment on office conditions. The study also attempted to determine the factors affecting the occupants' satisfaction with their building or office conditions. Post-occupancy evaluations were conducted using a structured questionnaire developed by the Built Environment Research Group at the University of Manchester, UK. Our questionnaires incorporate 22 factors relating to the internal environment and rate these in terms of "user satisfaction" and "degree of importance." The questions were modified to reflect the specific setting of the study and take into consideration the local conditions and climate in Malaysia. The overall mean satisfaction of the occupants toward their office environment was 5.35. The results were measured by a single item of overall liking of office conditions in general. Occupants were more satisfied with their state of health in the workplace, but they were extremely dissatisfied with the distance away from a window. The factor analysis divided the variables into three groups, namely intrusion, air quality, and office appearance. Structural equation modeling (SEM) was then used to determine which factor had the most significant influence on occupants' satisfaction: appearance. The findings from the study suggest that continuous improvement in aspects of the building's appearance needs to be supported with effective and comprehensive maintenance to sustain the occupants' satisfaction. PMID:25864077
Broadening the Bandwidth of Metamaterial Cloaks with Non-Foster Metasurfaces
Chen, Pai-Yen; Alu, Andrea
2013-01-01
We introduce the concept and practical design of broadband, ultrathin cloaks based on non-Foster, negatively capacitive metasurfaces. By using properly tailored, active frequency-selective screens conformal to an object, within the realm of practical realization, is shown to enable drastically reduced scattering over a wide frequency range in the microwave regime, orders of magnitude broader than any available passive cloaking technology. The proposed active cloak may impact not only invisibility and camouflaging, but also practical antenna and sensing applications.
International Nuclear Information System (INIS)
Very recently Farhat et al (2011, Phys. Rev. B 84 235105) suggested that arrays of invisibility cloaks may find important applications in low-interference communication, noninvasive probing, sensing and communication networks and so on. We report on the first experimental realization of such an array of broadband invisibility cloaks that operates in the visible frequency range. The wavelength and angular dependences of the cloak array performance have been studied. (paper)
The scattering of a cylindrical invisibility cloak: reduced parameters and optimization
Peng, L; L. Ran; Mortensen, N. A.
2011-01-01
Abstract We investigate the scattering of 2D cylindrical invisibility cloaks with simplified constitutive parameters with the assistance of scattering coefficients. We show that the scattering of the cloaks originates not only from the boundary conditions but also from the spatial variation of the component of permittivity/permeability. According to our formulation, we propose some restrictions to the invisibility cloak in order to minimize its scattering after the simplification has taken...
Invisibility cloaks with arbitrary geometries for layered and gradually changing backgrounds
Energy Technology Data Exchange (ETDEWEB)
Li, C; Yao, K; Li, F, E-mail: cli@mail.ie.ac.c [Institute of Electronics, Chinese Academy of Sciences, Beijing 100190 (China)
2009-09-21
Cloaks with arbitrary geometries are proposed which can make objects invisible in inhomogeneous backgrounds. The general and explicit expressions of the complex permittivity and permeability tensors are derived for cloaks embedded in layered and gradually changing media. The inner and the outer boundaries of the cloaks can be non-conformal with arbitrary shapes, which considerably improve the flexibility of the cloak applications. The interactions of electromagnetic waves with irregular cloaks are studied based on numerical simulations. The influences of the cloaked and uncloaked perfect electric conductor (PEC) cylinders upon the scattering fields of the multilayered backgrounds are quantitatively evaluated. The effect of loss on the cloaking performance has also been investigated. It is verified that cloaks with ideal parameters can smoothly deflect and guide the incoming beams to propagate around the shielded regions without disturbing the beams when they return to the inhomogeneous backgrounds. Therefore, the objects in the shielded region can be effectively invisible to the corresponding backgrounds. The performance of lossy cloaks will degrade with comparatively large power reduction of the transmitted beams.
Invisibility cloaks with arbitrary geometries for layered and gradually changing backgrounds
International Nuclear Information System (INIS)
Cloaks with arbitrary geometries are proposed which can make objects invisible in inhomogeneous backgrounds. The general and explicit expressions of the complex permittivity and permeability tensors are derived for cloaks embedded in layered and gradually changing media. The inner and the outer boundaries of the cloaks can be non-conformal with arbitrary shapes, which considerably improve the flexibility of the cloak applications. The interactions of electromagnetic waves with irregular cloaks are studied based on numerical simulations. The influences of the cloaked and uncloaked perfect electric conductor (PEC) cylinders upon the scattering fields of the multilayered backgrounds are quantitatively evaluated. The effect of loss on the cloaking performance has also been investigated. It is verified that cloaks with ideal parameters can smoothly deflect and guide the incoming beams to propagate around the shielded regions without disturbing the beams when they return to the inhomogeneous backgrounds. Therefore, the objects in the shielded region can be effectively invisible to the corresponding backgrounds. The performance of lossy cloaks will degrade with comparatively large power reduction of the transmitted beams.
Soil-Structure Interaction in RC Frame Buildings from Strong-Motion Recordings
Genes, Mehmet Cemal; DOĞANAY, Ela; BİKÇE, Murat; KAÇIN, Selçuk
2011-01-01
In this study, Soil-structure interaction (SSI) of Reinforced Concrete (RC) buildings which are instrumented by building monitoring systems is detected and identified. SSI can have a major influence on the seismic response of buildings constructed on soft soils. The dominant frequency recorded for a building subjected to SSI is always smaller than the dominant frequencies of the fixed-based building, and of the foundation when no building is present. The identification of SSI refers to extrac...
Semolič, Živa
2013-01-01
In the thesis an analysis and design of characteristic elements of the load-bearing structure for the selected multi-story building was undertaken. The building is located in Ljubljana and is a constituent of a building complex. Buildings are detached by expansion joints so one can be addressed separately. Load-bearing structure consists of monolithic reinforced concrete floor panels, reinforced concrete walls and reinforced concrete frames. The building was planned and designed according to ...
FEM Updating of the Heritage Court Building Structure
DEFF Research Database (Denmark)
Ventura, C. E.; Brincker, Rune; Dascotte, E.; Andersen, P.
starting model of the structure was developed from the information provided in the design documentation of the building. Different parameters of the model were then modified using an automated procedure to improve the correlation between measured and calculated modal parameters. Careful attention was...... placed to the selection of the parameters to be modified by the updating software in order to ensure that the necessary changes to the model were realistic and physically realisable and meaningful. The paper highlights the model updating process and provides an assessment of the usefulness of using an...... automatic model updating procedure combined with results from an output-only modal identification....
Equipment and building structures ageing management for WWER type NPPs
International Nuclear Information System (INIS)
This report presents the working group 'Equipment and building structures ageing management for WWER type NPPs' activities. The analysis of experience in ageing management, recommendations for regulatory guidelines on ageing management, investigation of case studies, definition suitable communication channels among regulators for ageing related data are given. Analyses of water chemistry, inspection data (safety margins criteria), plugging criteria, volume and time of ECT implementation in all WWER countries are presented. The results of Working group activity show that it is advisable to concentrate efforts on: set up the permanent communication channel among regulators, collection of regulatory criteria for WWER type NPP key components based on understanding of ageing mechanisms and data collection
Fuzzy sensitivity analysis for reliability assessment of building structures
Kala, Zdeněk
2016-06-01
The mathematical concept of fuzzy sensitivity analysis, which studies the effects of the fuzziness of input fuzzy numbers on the fuzziness of the output fuzzy number, is described in the article. The output fuzzy number is evaluated using Zadeh's general extension principle. The contribution of stochastic and fuzzy uncertainty in reliability analysis tasks of building structures is discussed. The algorithm of fuzzy sensitivity analysis is an alternative to stochastic sensitivity analysis in tasks in which input and output variables are considered as fuzzy numbers.
Effective Structures of Tamped Foundations of Frame Buildings
Directory of Open Access Journals (Sweden)
Bartolomey Leonid
2016-01-01
Full Text Available The application results of foundations in a tamped ditch in complex geotechnical conditions are strongly considered. The article informs about the experience of the effective foundation application instead of pile foundations. Also, a special attention is given to stress-strain analysis in the active zone of the soil basement of the foundation in a tamped ditch. The article exposes innovative technology of transformation the soil materials structure. Presents the results of studies of innovative soil materials state in the field of geotechnics and foundation engineering. This article seems to be interesting for those who work in the field of building construction and geotechnics.
Cloud immersion building shielding factors for US residential structures
International Nuclear Information System (INIS)
This paper presents validated building shielding factors designed for contemporary US housing-stock under an idealized, yet realistic, exposure scenario within a semi-infinite cloud of radioactive material. The building shielding factors are intended for use in emergency planning and level three probabilistic risk assessments for a variety of postulated radiological events in which a realistic assessment is necessary to better understand the potential risks for accident mitigation and emergency response planning. Factors are calculated from detailed computational housing-units models using the general-purpose Monte Carlo N-Particle computational code, MCNP5, and are benchmarked from a series of narrow- and broad-beam measurements analyzing the shielding effectiveness of ten common general-purpose construction materials and ten shielding models representing the primary weather barriers (walls and roofs) of likely US housing-stock. Each model was designed to scale based on common residential construction practices and include, to the extent practical, all structurally significant components important for shielding against ionizing radiation. Calculations were performed for floor-specific locations as well as for computing a weighted-average representative building shielding factor for single- and multi-story detached homes, both with and without basement, as well for single-wide manufactured housing-units. (paper)
Acoustic carpet cloak based on an ultrathin metasurface
Esfahlani, Hussein; Karkar, Sami; Lissek, Herve; Mosig, Juan R.
2016-07-01
An acoustic metasurface carpet cloak based on membrane-capped cavities is proposed and investigated numerically. This design has been chosen for allowing ultrathin geometries, although adapted to airborne sound frequencies in the range of 1 kHz (λ ≈30 cm), surpassing the designs reported in the literature in terms of thinness. A formulation of generalized Snell's laws is first proposed, mapping the directions of the incident and reflected waves to the metasurface phase function. This relation is then applied to achieve a prescribed wavefront reflection direction, for a given incident direction, by controlling the acoustic impedance grading along the metasurface. The carpet cloak performance of the proposed acoustic metasurface is then assessed on a triangular bump obstacle, generally considered as a baseline configuration in the literature.
Surface Wave Cloak from Graded Refractive Index Nanocomposites.
La Spada, L; McManus, T M; Dyke, A; Haq, S; Zhang, L; Cheng, Q; Hao, Y
2016-01-01
Recently, a great deal of interest has been re-emerged on the possibility to manipulate surface waves, in particular, towards the THz and optical regime. Both concepts of Transformation Optics (TO) and metamaterials have been regarded as one of key enablers for such applications in applied electromagnetics. In this paper, we experimentally demonstrate for the first time a dielectric surface wave cloak from engineered gradient index materials to illustrate the possibility of using nanocomposites to control surface wave propagation through advanced additive manufacturing. The device is designed analytically and validated through numerical simulations and measurements, showing good agreement and performance as an effective surface wave cloak. The underlying design approach has much wider applications, which span from microwave to optics for the control of surface plasmon polaritons (SPPs) and radiation of nanoantennas. PMID:27416815
Surface Wave Cloak from Graded Refractive Index Nanocomposites
La Spada, L.; McManus, T. M.; Dyke, A.; Haq, S.; Zhang, L.; Cheng, Q.; Hao, Y.
2016-07-01
Recently, a great deal of interest has been re-emerged on the possibility to manipulate surface waves, in particular, towards the THz and optical regime. Both concepts of Transformation Optics (TO) and metamaterials have been regarded as one of key enablers for such applications in applied electromagnetics. In this paper, we experimentally demonstrate for the first time a dielectric surface wave cloak from engineered gradient index materials to illustrate the possibility of using nanocomposites to control surface wave propagation through advanced additive manufacturing. The device is designed analytically and validated through numerical simulations and measurements, showing good agreement and performance as an effective surface wave cloak. The underlying design approach has much wider applications, which span from microwave to optics for the control of surface plasmon polaritons (SPPs) and radiation of nanoantennas.
Acoustic carpet cloak based on an ultrathin metasurface
Esfahlani, Hussein; Karkar, Sami; Lissek, Herve; Mosig, Juan R.
2016-01-01
An acoustic metasurface carpet cloak based on membrane-capped cavities is proposed and investigated numerically. This design has been chosen for allowing ultrathin geometries, although adapted to airborne sound frequencies in the range of 1 kHz (λ≈30 cm), surpassing the designs reported in the literature in terms of thinness. A formulation of generalized Snell's laws is first proposed, mapping the directions of the incident and reflected waves to the metasurface phase function. This relation ...
Hiding a Realistic Object Using a Broadband Terahertz Invisibility Cloak
Fan Zhou; Yongjun Bao; Wei Cao; Stuart, Colin T.; Jianqiang Gu; Weili Zhang; Cheng Sun
2011-01-01
The invisibility cloak has been a long-standing dream for many researchers over the decades. The introduction of transformational optics has revitalized this field by providing a general method to design material distributions to hide the subject from detection. By transforming space and light propagation, a three-dimensional (3D) object is perceived as having a reduced number of dimensions, in the form of points, lines, and thin sheets, making it "undetectable" judging from the scattered fie...
Infrared Cloaking, Stealth, and the Second Law of Thermodynamics
Daniel P. Sheehan
2012-01-01
Infrared signature management (IRSM) has been a primary aeronautical concern for over 50 years. Most strategies and technologies are limited by the second law of thermodynamics. In this article, IRSM is considered in light of theoretical developments over the last 15 years that have put the absolute status of the second law into doubt and that might open the door to a new class of broadband IR stealth and cloaking techniques. Following a brief overview of IRSM and its current thermodynamic li...
The PROBE Framework for the Personalized Cloaking of Private Locations
Maria Luisa Damiani; Elisa Bertino; Claudio Silvestri
2010-01-01
The widespread adoption of location-based services (LBS) raises increasing concerns for the protection of personal location information. A common strategy, referred to as obfuscation (or cloaking), to protect location privacy is based on forwarding the LBS provider a coarse user location instead of the actual user location. Conventional approaches, based on such technique, are however based only on geometric methods and therefore are unable to assure privacy when the adversary is aware of the...
The PROBE Framework for the Personalized Cloaking of Private Locations
Directory of Open Access Journals (Sweden)
Maria Luisa Damiani
2010-08-01
Full Text Available The widespread adoption of location-based services (LBS raises increasing concerns for the protection of personal location information. A common strategy, referred to as obfuscation (or cloaking, to protect location privacy is based on forwarding the LBS provider a coarse user location instead of the actual user location. Conventional approaches, based on such technique, are however based only on geometric methods and therefore are unable to assure privacy when the adversary is aware of the geographical context, in particular of the semantic locations and the statistical distribution of positions in the given space. This paper provides a comprehensive solution to this problem. We present a novel privacy model and an architectural framework for the personalized cloaking of semantic locations. In ourmodel, a cloaked location is an uncertainty regionwhich satisfies the privacy constraints specified by the user in the privacy profile (obfuscated location. We propose a strategy for generating obfuscated locations and evaluate different algorithms which implement efficiently such a strategy. The paper includes several experimental results assessing performance, storage requirements and accuracy for the approach. The paper also discusses the system architecture and shows that the approach can be deployed also for clients running on small devices.
Soil-structure interaction in fuel handling building
Energy Technology Data Exchange (ETDEWEB)
Elaidi, B.M.; Eissa, M.A. [Altran Corp., Boston, MA (United States)
1998-05-01
This paper presents an accurate three-dimensional seismic soil-structure interaction analysis for large structures. The method is applied to the fuel building in nuclear power plants. The analysis is performed numerically in the frequency domain and the responses are obtained by inverse Fourier transformation. The size of the structure matrices is reduced by transforming the equation of motion to the modal coordinate system. The soil is simulated as a layered media on top of viscoelastic half space. Soil impedance matrices are calculated from the principles of continuum mechanics and account for soil stiffness and energy dissipation. Effects of embedment on the field equations is incorporated through the scattering matrices or by simply scaling the soil impedance. Finite element methods are used to discretize the concrete foundation for the generation of the soil interaction matrices. Decoupling of the sloshing water in the spent fuel pools and the free-standing spent fuel racks is simulated. The input seismic motions are defined by three artificial time history accelerations. These input motions are generated to match the ground design basis response spectra and the target power spectral density function. The methods described in this paper can handle arbitrary foundation layouts, allows for large structural models, and accurately represents the soil impedance. Time history acceleration responses were subsequently used to generate floor response spectra at applicable damping values. (orig.) 6 refs.
Soil-structure interaction in fuel handling building
International Nuclear Information System (INIS)
This paper presents an accurate three-dimensional seismic soil-structure interaction analysis for large structures. The method is applied to the fuel building in nuclear power plants. The analysis is performed numerically in the frequency domain and the responses are obtained by inverse Fourier transformation. The size of the structure matrices is reduced by transforming the equation of motion to the modal coordinate system. The soil is simulated as a layered media on top of viscoelastic half space. Soil impedance matrices are calculated from the principles of continuum mechanics and account for soil stiffness and energy dissipation. Effects of embedment on the field equations is incorporated through the scattering matrices or by simply scaling the soil impedance. Finite element methods are used to discretize the concrete foundation for the generation of the soil interaction matrices. Decoupling of the sloshing water in the spent fuel pools and the free-standing spent fuel racks is simulated. The input seismic motions are defined by three artificial time history accelerations. These input motions are generated to match the ground design basis response spectra and the target power spectral density function. The methods described in this paper can handle arbitrary foundation layouts, allows for large structural models, and accurately represents the soil impedance. Time history acceleration responses were subsequently used to generate floor response spectra at applicable damping values. (orig.)
Development of cyber-based autonomous structural integrity assessment system for building structures
Kurata, M.; Fujita, K.; Li, X.; Yamazaki, T.; Yamaguchi, M.
2013-04-01
For the application of structural health monitoring (SHM) system to the post-earthquake damage screening of building structures, an immediate evaluation of the degree of damage in primary structural components is a challenging task. To increase the resolution in damage detection above a certain level to detect damage in individual components, a SHM requires the use of a dense array of sensors deployed to building structures. In order to deal with a large amount of data acquired by the sensing network and to distribute quick safety alerts on the condition of earthquake-affected buildings, a SHM system that is connected with a cyberinfrastructure specifically designed for the autonomous structural integrity assessment of buildings is developed. In the system, big data transferred from a dense sensing network is automatically stored and processed to extract damage features using a PostgresSQL relational database and embedded local damage detection algorithms. In a benchmark study, the schema of the SHM system is specifically designed to function with a built-in local damage detection algorithm that needs a comparative study of current dataset with past reference dataset. To visualize the results of the damage detection analysis, a PHP-based web-viewer is also designed for the SHM system. Finally, the performance of the developed cyber-based SHM system is evaluated through a series of the damage detection tests on a 5-story steel testbed frame that can replicate damage in beams and columns.
Institute of Scientific and Technical Information of China (English)
无
2006-01-01
Based on the theory of coordinating action of building ground, foundation and structure, this paper presents a modified method for calculating additional stresses on buildings in mining areas by considering the joint effect of curvature deformation and horizontal deformation on buildings. It points out that for buildings over the coal pillar, it is advisable to soften the intermediate ground of buildings when they are affected by mining. For buildings over the goaf, it is preferable to soften the ground at both ends of buildings. In order to enhance the ability of a building to resist tensile deformation, the key measure is to reinforce the bottom foundation of the building. In addition, the concept of "angle of break of building" is proposed. It is because of this angle that the protecting coal pillar is left, which is a better solution than prevailing solutions The findings provide a more scientific basis for mining under buildings.
Fabrication and erection of special building structures at the Rovno NPP third unit
International Nuclear Information System (INIS)
It is described how works on fabrication and erection of special building structures in the reactor section, a special building and a stand-by diesel-generator station at the Rovno Unit-3 are organized
Three-dimensional magnetic cloak working from d.c. to 250 kHz
Zhu, Jianfei; Jiang, Wei; Liu, Yichao; Yin, Ge; Yuan, Jun; He, Sailing; Ma, Yungui
2015-11-01
Invisible cloaking is one of the major outcomes of the metamaterial research, but the practical potential, in particular for high frequencies (for example, microwave to visible light), is fatally challenged by the complex material properties they usually demand. On the other hand, it will be advantageous and also technologically instrumental to design cloaking devices for applications at low frequencies where electromagnetic components are favourably uncoupled. In this work, we vastly develop the bilayer approach to create a three-dimensional magnetic cloak able to work in both static and dynamic fields. Under the quasi-static approximation, we demonstrate a perfect magnetic cloaking device with a large frequency band from 0 to 250 kHz. The practical potential of our device is experimentally verified by using a commercial metal detector, which may lead us to having a real cloaking application where the dynamic magnetic field can be manipulated in desired ways.
Directional cloaking of flexural waves in a plate with a locally resonant metamaterial.
Colombi, Andrea; Roux, Philippe; Guenneau, Sebastien; Rupin, Matthieu
2015-04-01
This paper deals with the numerical design of a directional invisibility cloak for backward scattered elastic waves propagating in a thin plate (A0 Lamb waves). The directional cloak is based on a set of resonating beams that are attached perpendicular to the plate and are arranged at a sub-wavelength scale in ten concentric rings. The exotic effective properties of this locally resonant metamaterial ensure coexistence of bandgaps and directional cloaking for certain beam configurations over a large frequency band. The best directional cloaking was obtained when the resonators' length decreases from the central to the outermost ring. In this case, flexural waves experience a vanishing index of refraction when they cross the outer layers, leading to a frequency bandgap that protects the central part of the cloak. Numerical simulation shows that there is no back-scattering in these configurations. These results might have applications in the design of seismic-wave protection devices. PMID:25920831
Experimental verification of free-space singular boundary conditions in an invisibility cloak
Wu, Qiannan; Gao, Fei; Song, Zhengyong; Lin, Xiao; Zhang, Youming; Chen, Huanyang; Zhang, Baile
2016-04-01
A major issue in invisibility cloaking, which caused intense mathematical discussions in the past few years but still remains physically elusive, is the plausible singular boundary conditions associated with the singular metamaterials at the inner boundary of an invisibility cloak. The perfect cloaking phenomenon, as originally proposed by Pendry et al for electromagnetic waves, cannot be treated as physical before a realistic inner boundary of a cloak is demonstrated. Although a recent demonstration has been done in a waveguide environment, the exotic singular boundary conditions should apply to a general environment as in free space. Here we fabricate a metamaterial surface that exhibits the singular boundary conditions and demonstrate its performance in free space. Particularly, the phase information of waves reflected from this metamaterial surface is explicitly measured, confirming the singular responses of boundary conditions for an invisibility cloak.
Design method for electromagnetic cloak with arbitrary shapes based on Laplace's equation.
Hu, Jin; Zhou, Xiaoming; Hu, Gengkai
2009-02-01
In transformation optics, the space transformation is viewed as the deformation of a material. The permittivity and permeability tensors in the transformed space are found to correlate with the deformation field of the material. By solving the Laplace's equation, which describes how the material will deform during a transformation, we can design electromagnetic cloaks with arbitrary shapes if the boundary conditions of the cloak are considered. As examples, the material parameters of the spherical and elliptical cylindrical cloaks are derived based on the analytical solutions of the Laplace's equation. For cloaks with irregular shapes, the material parameters of the transformation medium are determined numerically by solving the Laplace's equation. Full-wave simulations based on the Maxwell's equations validate the designed cloaks. The proposed method can be easily extended to design other transformation materials for electromagnetic and acoustic wave phenomena. PMID:19188959
A self-assembled three-dimensional cloak in the visible
Mühlig, Stefan
2013-08-07
An invisibility cloak has been designed, realized and characterized. The cloak hides free-standing sub-wavelength three-dimensional objects at the short wavelength edge of the visible spectrum. By a bottom-up approach the cloak was self-assembled around the object. Such fabrication approach constitutes a further important step towards real world applications of cloaking; leaving the realm of curiosity. The cloak and the way it was fabricated opens an avenue for many spectacular nanooptical applications such as non-disturbing sensors and photo-detectors, highly efficient solar cells, or optical nanoantenna arrays with strongly suppressed cross-talk to mention only a few. Our results rely on the successful combination of concepts from various disciplines, i.e. chemistry, material science, and plasmonics. Consequently, this work will stimulate these fields by unraveling new paths for future research.
Three-dimensional magnetic cloak working from DC to 250 kHz
Zhu, Jianfei; Liu, Yichao; Yin, Ge; Yuan, Jun; He, Sailing; Ma, Yungui
2015-01-01
Invisible cloaking is one of major outcomes of the metamaterial research, but the practical potential, in particular for high frequencies (e.g., microwave to visible light), is fatally challenged by the complex material properties they usually demand. On the other hand, it will be advantageous and also technologically instrumental to design cloaking devices for applications at low frequencies where electromagnetic components are favorably uncoupled. In this work, we vastly develop the bilayer approach to create a three-dimensional magnetic cloak able to work in both static and dynamic fields. Under the quasi-static approximation, we demonstrate a perfect magnetic cloaking device with a large frequency band from zero to 250 kHz. The practical potential of our device is experimentally verified by using a commercial metal detector, which may lead us to having a real cloaking application where the dynamic magnetic field can be manipulated in desired ways.
Analysis of load-bearing structure of a multi-storey office building in Idrija
Novak, Primož
2013-01-01
This thesis presents the design and static analysis of the load-bearing construction for the selected multi-storey reinforced concrete office building. The building is located in Idrija and consists of two parts, office building and hall, which are separated with dilatation. The thesis is focused on the Office building with vertical load-bearing structure made as a frame structure, consisting of columns and beams, which are interconnect with the solid reinforced concrete slabs. Load-bearing c...
A Review of Current Researches on Blast Load Effects on Building Structures in China
Institute of Scientific and Technical Information of China (English)
LI Zhongxian; DU Hao; BAO Chunxiao
2006-01-01
The damages of building structures subjected to multifarious explosions cause huge losses of lives and property.It is the reason why the blast resistance and explosion protection of building structures become an important research topic in the civil engineering field all over the world.This paper provides an overview of the research work in China on blast loads effect on building structures.It includes modeling blast shock wave propagation and their effects,the dynamic responses of various building structures under blast loads and the measures to strengthen the building structures against blast loads.The paper also discusses the achievements and further work that needs be done for a better understanding of the blast loads' effects on building structures,and for deriving effective and economic techniques to design new or to strengthen existing structures.
MUNI Ways and Structures Building Integrated Solar Membrane Project
Energy Technology Data Exchange (ETDEWEB)
Smith, Randall
2014-07-03
The initial goal of the MUNI Ways and Structures Building Integrated Solar Membrane Installation Project was for the City and County of San Francisco (CCSF) to gain experience using the integrated higher efficiency solar photovoltaic (PV) single-ply membrane product, as it differs from the conventional, low efficiency, thin-film PV products, to determine the feasibility of success of larger deployment. As several of CCSF’s municipal rooftops are constrained with respect to weight restrictions, staff of the Energy Generation Group of the San Francisco Public Utilities Commission (SFPUC) proposed to install a solar PV system using single-ply membrane The installation of the 100 kW (DC-STC) lightweight photo voltaic (PV) system at the MUNI Ways and Structures Center (700 Pennsylvania Ave., San Francisco) is a continuation of the commitment of the City and County of San Francisco (CCSF) to increase the pace of municipal solar development, and serve its municipal facilities with clean renewable energy. The fourteen (14) solar photovoltaic systems that have already been installed at CCSF municipal facilities are assisting in the reduction of fossil-fuel use, and reduction of greenhouse gases from fossil combustion. The MUNI Ways & Structures Center roof has a relatively low weight-bearing capacity (3.25 pounds per square foot) and use of traditional crystalline panels was therefore rejected. Consequently it was decided to use the best available highest efficiency Building-Integrated PV (BIPV) technology, with consideration for reliability and experience of the manufacturer which can meet the low weight-bearing capacity criteria. The original goal of the project was to provide an opportunity to monitor the results of the BIPV technology and compare these results to other City and County of San Francisco installed PV systems. The MUNI Ways and Structures Center was acquired from the Cookson Doors Company, which had run the Center for many decades. The building was
Smolyaninov, Igor I; Smolyaninov, Alexei I
2014-01-01
Cobalt nanoparticle-based ferrofluid in the presence of external magnetic field forms a self-assembled hyperbolic metamaterial. Wave equation describing propagation of extraordinary light inside the ferrofluid exhibits 2+1 dimensional Lorentz symmetry. The role of time in the corresponding effective 3D Minkowski spacetime is played by the spatial coordinate directed along the periodic nanoparticle chains aligned by the magnetic field. Here we present a microscopic study of point, linear and volume defects of the nanoparticle chain structure and demonstrate that they may exhibit strong similarities with such Minkowski spacetime defects as magnetic monopoles, cosmic strings and the recently proposed spacetime cloaks. Experimental observations of such defects are described.
Directory of Open Access Journals (Sweden)
Jian Zhu
2015-07-01
Full Text Available We present the design, implementation and detailed performance analysis for a class of trapeziform and flat acoustic cloaks. An effective large invisible area is obtained compared with the traditional carpet cloak. The cloaks are realized with homogeneous metamaterials which are made of periodic arrangements of subwavelength unit cells composed of steel embedded in air. The microstructures and its effective parameters of the cloaks are determined quickly and precisely in a broadband frequency range by using the effective medium theory and the proposed parameters optimization method. The invisibility capability of the cloaks can be controlled by the variation of the key design parameters and scale factor which are proved to have more influence on the performance in the near field than that in the far field. Different designs are suitable for different application situations. Good cloaking performance demonstrates that such a device can be physically realized with natural materials which will greatly promote the real applications of invisibility cloak.
Zhu, Jian; Chen, Tianning; Liang, Qingxuan; Wang, Xiaopeng; Xiong, Jie; Jiang, Ping
2015-07-01
We present the design, implementation and detailed performance analysis for a class of trapeziform and flat acoustic cloaks. An effective large invisible area is obtained compared with the traditional carpet cloak. The cloaks are realized with homogeneous metamaterials which are made of periodic arrangements of subwavelength unit cells composed of steel embedded in air. The microstructures and its effective parameters of the cloaks are determined quickly and precisely in a broadband frequency range by using the effective medium theory and the proposed parameters optimization method. The invisibility capability of the cloaks can be controlled by the variation of the key design parameters and scale factor which are proved to have more influence on the performance in the near field than that in the far field. Different designs are suitable for different application situations. Good cloaking performance demonstrates that such a device can be physically realized with natural materials which will greatly promote the real applications of invisibility cloak.
Horizontal cloaking and vertical reflection by transformation acoustics
Directory of Open Access Journals (Sweden)
Min Kyung Lee
2013-05-01
Full Text Available This investigation shows that if an acoustic metamaterial bounded by an external rectangle and an internal circular cavity is properly engineered by a set of transformation equations that satisfy certain requirements, it can virtually cloak an object against incoming acoustic waves in one direction and make an incoming wave along the orthogonal direction reflected by an object located inside its inner cavity. The specific transformation equations realizing the metamaterial are suggested and an analysis is carried out to investigate the wave phenomena taking place along the cavity boundary.
Global Analysis of Tall Buildings with Tubed Mega Frame Structures
Svärd, Jenny; Partovi, Arezo
2016-01-01
Today, tall buildings are generally built with a central core that transfers the loads down to the ground. The central core takes up a large part of the floor space and there is less room for the actual purpose of the building, such as offices and apartments. The consequence of this is also less rental profit. At a certain height of the building, the central core will not alone manage to keep the building stable. Therefore it needs to be connected with outriggers to withstand the horizontal f...
Lafarge, Florent; Descombes, Xavier; Zerubia, Josiane; Deseilligny, Marc-Pierrot
2006-01-01
We present an automatic 3D city model of dense urban areas from high resolution satellite data. The proposed method is developed using a structural approach : we construct complex buildings by merging simple parametric models with rectangular ground footprint. To do so, an automatic building extraction method based on marked point processes is used to provide rectangular building footprints. A collection of 3D parametric models is defined in order to be fixed onto these building footprints. A...
Structure optimization of energy supply systems in tertiary sector buildings
Energy Technology Data Exchange (ETDEWEB)
Lozano, Miguel A.; Ramos, Jose C.; Carvalho, Monica; Serra, Luis M. [Grupo GITSE - I3A, Department of Mechanical Engineering, Universidad de Zaragoza, 50018 Zaragoza (Spain)
2009-10-15
Trigeneration systems, also known as Combined Heat, Cooling and Power (CHCP) systems, are interesting alternatives to supply different energy services in urban districts and in large buildings, particularly in warm areas such as Mediterranean countries. These systems can provide substantial benefits from economic, energetic, and environmental viewpoints, since the cogenerated heat can be used for heating in winter as well as cooling in summer with an absorption refrigerator. This paper develops an optimization model using Mixed Integer Linear Programming (MILP) to determine the type, number and capacity of equipment in CHCP systems installed in the tertiary sector as well as to establish the optimal operation mode for the different plant components on an hour-by-hour basis throughout the year. The objective function to be minimized is the annual total cost. The optimization model considers the legal constraints imposed to feed the surplus autogenerated electricity into the grid at a regulated feed-in tariff. The optimization model is applied to design a system providing energy services for a hospital located in the city of Zaragoza (Spain). The effects of the financial market conditions and energy prices in the optimal structure of the system are analyzed. (author)
Study on reactor building structure using ultrahigh strength materials, 5
International Nuclear Information System (INIS)
Reinforced concrete (RC) shear walls are the main members of a reactor building for the aseismatic design. The characteristics of nonlinear behavior have been clarified by a number of experimental studies, and the reliability of the nonlinear analysis of RC structures by FEM has been improved by the studies on the constitutive equation for concrete and the simulation analysis of test results. However, the characteristics of the RC shear walls made of ultrahigh strength materials have not been sufficiently studied. In this paper, the nonlinear analysis of the RC shear walls made of ultrahigh strength materials is discussed. Based on the results of a series of the material test and pure shear test on ultrahigh strength materials, the simulation analysis of bending shear test was performed by three-dimensional nonlinear FEM. The specimens used for the bending shear test were single story, single span model shear walls. The analytical method, the modeling of concrete and reinforcing bars, the properties of the materials used and the results of analysis on the effects of concrete strength and the quantity and grade of bars are reported. (K.I.)
How to Build Your Network? A Structural Analysis
Moskvina, Anastasia
2016-01-01
Creating new ties in a social network facilitates knowledge exchange and affects positional advantage. In this paper, we study the process, which we call network building, of establishing ties between two existing social networks in order to reach certain structural goals. We focus on the case when one of the two networks consists only of a single member and motivate this case from two perspectives. The first perspective is socialization: we ask how a newcomer can forge relationships with an existing network to place herself at the center. We prove that obtaining optimal solutions to this problem is NP-complete, and present several efficient algorithms to solve this problem and compare them with each other. The second perspective is network expansion: we investigate how a network may preserve or reduce its diameter through linking with a new node, hence ensuring small distance between its members. We give two algorithms for this problem. For both perspectives the experiment demonstrates that a small number of...
Aboumoussa, Walid
2014-01-01
Structures placed on hillsides often present a number of challenges and a limited number of economical choices for site design. An option sometimes employed is to use the building frame as a retaining element, comprising a Rigidly Framed Earth Retaining Structure (RFERS). The relationship between temperature and earth pressure acting on RFERS, is explored in this monograph through a 4.5 year monitoring program of a heavily instrumented in service structure. The data indicated that the coefficient of earth pressure behind the monitored RFERS had a strong linear correlation with temperature. The study also revealed that thermal cycles, rather than lateral earth pressure, were the cause of failure in many structural elements. The book demonstrates that depending on the relative stiffness of the retained soil mass and that of the structural frame, the developed lateral earth pressure, during thermal expansion, can reach magnitudes several times larger than those determined using classical earth pressure theories....
Agent Types and Structures based on Analysis of Building Design
DEFF Research Database (Denmark)
Hartvig, Susanne C
Based on an anaysis of building design an initial division of design agent into five classes: information collectors, generators, modifiers amd evaluators is presented.......Based on an anaysis of building design an initial division of design agent into five classes: information collectors, generators, modifiers amd evaluators is presented....
Chen, Ming-Ji; Pei, Yong-Mao; Fang, Dai-Ning
2010-03-01
The classic anisotropic spherical cloak can be mimicked by many alternating thin layers of isotropic metamaterials [Qiu et al. Phys. Rev. E 79 (2009) 047602]. We propose an improved method of designing permittivity and permeability in each isotropic layer, which eliminates the jumping of the refractive index at the interface. Multilayered spherical cloaks designed by the present method perform much better than those by Qiu et al., especially for forward scattering. It is found that the ratio of layer thickness to the operating wavelength plays an important role in achieving invisibility. The presented cloak should be discretized to at least 40 layers to meet the thickness threshold corresponding to 10% scattering.
Energy Technology Data Exchange (ETDEWEB)
Novitsky, Andrey [Department of Theoretical Physics, Belarusian State University, Nezavisimosti Avenue 4, 220050 Minsk (Belarus); Qiu, C-W [Research Laboratory of Electronics, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139 (United States); Zouhdi, Said [Laboratoire de Genie Electrique de Paris, SUPELEC, Plateau de Moulon 91192, Gif-sur-Yvette (France)], E-mail: eleqc@nus.edu.sg
2009-11-15
Based on the concept of the cloak generating function, we propose an implicit transformation-independent method for the required parameters of spherical cloaks without knowing the needed coordinate transformation beforehand. A non-ideal discrete model is used to calculate and optimize the total scattering cross-sections of different profiles of the generating function. A bell-shaped quadratic spherical cloak is found to be the best candidate, which is further optimized by controlling the design parameters involved. Such improved invisibility is steady even when the model is highly discretized.
General scaling limitations of ground-plane and isolated-object cloaks
Energy Technology Data Exchange (ETDEWEB)
Hashemi, Hila; Johnson, Steven G. [Department of Mathematics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Oskooi, A. [Department of Electronic Science and Engineering, Kyoto University (Japan); Joannopoulos, J. D. [Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)
2011-08-15
We prove that, for arbitrary three-dimensional transformation-based invisibility cloaking of an object above a ground plane or of isolated objects, there are practical constraints that increase with the object size. In particular, we show that the cloak thickness must scale proportionally to the thickness of the object being cloaked, assuming bounded refractive indices, and that absorption discrepancies and other imperfections must scale inversely with the object thickness. For isolated objects, we also show that bounded refractive indices imply a lower bound on the effective cross section.
Employing pre-stress to generate finite cloaks for antiplane elastic waves
Parnell, William J; Shearer, Tom
2012-01-01
It is shown that nonlinear elastic pre-stress of neo-Hookean hyperelastic materials can be used as a mechanism to generate finite cloaks and thus render objects near-invisible to incoming antiplane elastic waves. This approach appears to negate the requirement for special cloaking metamaterials with inhomogeneous and anisotropic material properties in this case. These properties are induced naturally by virtue of the pre-stress. This appears to provide a mechanism for broadband cloaking since dispersive effects due to metamaterial microstructure will not arise.
Directory of Open Access Journals (Sweden)
G. D. Shmelev
2011-11-01
Full Text Available Problem statement. Existing approaches to assessing reliability of building structures are basedon the model which involves exponential distribution. Such a model can be applied only for thesystems with abrupt failures. However, failures in building systems are usually caused by the wear.Results. The analysis of the correctness of calculations and forecasting reliability of buildingstructures is performed using exponentiation distribution. Wrongfulness of the use of the modelsfor assessment of reliability of building structures which are currently operated and have cumulativewear is shown with examples. An approach involving the linearization method is proposed.Conclusions. The approach proposed is straightforward to use, takes into account the changes instructure carrying capacity and does not contain inaccuracies and errors peculiar to the methodsdesigned on the exponential distribution models.
Biomimetic approach for liquid encapsulation with nanofibrillar cloaks.
Mele, Elisa; Bayer, Ilker S; Nanni, Gabriele; Heredia-Guerrero, José Alejandro; Ruffilli, Roberta; Ayadi, Farouk; Marini, Lara; Cingolani, Roberto; Athanassiou, Athanassia
2014-03-18
Technologies that are able to handle microvolumes of liquids, such as microfluidics and liquid marbles, are attractive for applications that include miniaturized biological and chemical reactors, sensors, microactuators, and drug delivery systems. Inspired from natural fibrous envelopes, here, we present an innovative approach for liquid encapsulation and manipulation using electrospun nanofibers. We demonstrated the realization of non-wetting soft solids consisting of a liquid core wrapped in a hydrophobic fibrillar cloak of a fluoroacrylic copolymer and cellulose acetate. By properly controlling the wetting and mechanical properties of the fibers, we created final architectures with tunable mechanical robustness that were stable on a wide range of substrates (from paper to glass) and floated on liquid surfaces. Remarkably, the realized fiber-coated drops endured vortex mixing in a continuous oil phase at high stirring speed without bursting or water losses, favoring mixing processes inside the entrapped liquid volume. Moreover, the produced cloak can be easily functionalized by incorporating functional particles, active molecules, or drugs inside the nanofibers. PMID:24564574
The model of intellectual support of decision-making in building structures condition management
Directory of Open Access Journals (Sweden)
Velichkin V.Z.
2012-05-01
Full Text Available Popular methods of decision-making in building structures condition management do not fully consider peculiarities of their up-to-date operation. These approaches do not take into account the kinds of uncertainty occurring at a building designing stage and taking place while monitoring. It leads to the decrease in building targeted application efficiency and increase of controlling organization costs. The following approach suggests the improvement in the decision-making support systems by integration of expert knowledge and experience with tool and visual building structure control results.The purpose of the paper is effective decision-making aimed at uncertainty level decrease in the process of detection of operational impacts on building structures for the required durability provision. This purpose is achieved by artificial intelligence element application (fuzzy sets in the joint analysis of retrospective, current and expert information on the building structure state. The authors suggest selecting building structure state controlling actions with the help of fuzzy conclusions obtained by the usage of designed algorithms and calculated procedures. The applicability of the given approach was proved by the calculated example. A grounded variant of decision on the building structure state intellectual control was submitted (a damaged building wall.On the basis of these results the conclusions on the application field and conditions of the designed algorithms and model were made.
Structural Identification And Seismic Analysis Of An Existing Masonry Building
International Nuclear Information System (INIS)
The paper presents the diagnostic investigation and the seismic analysis performed on an ancient masonry building in Florence. The building has historical interest and is subjected to conservative restrictions. The investigation involves a preliminary phase concerning the research of the historic documents and a second phase of execution of in situ and laboratory tests to detect the mechanical characteristics of the masonry. This investigation was conceived in order to obtain the 'LC2 Knowledge Level' and to perform the non-linear pushover analysis according to the new Italian Standards for seismic upgrading of existing masonry buildings
Bernety, Hossein M; Yakovlev, Alexander B
2015-05-13
In this paper, we present a novel analytical approach for cloaking of dielectric and metallic elliptical cylinders with a graphene monolayer and a nanostructured graphene metasurface at low-terahertz frequencies. The analytical approach is based on the solution of the electromagnetic scattering problem in terms of elliptical waves represented by the radial and angular even and odd Mathieu functions, with the use of sheet impedance boundary conditions at the metasurface. It is shown that scattering cancellation occurs for all incident and observation angles. A special case concerns cloaking of a 2D metallic strip represented by a degenerated ellipse, wherein the focal points of the cloak metasurface correspond to the edges of the strip. The analytical approach has been extended in order to cloak a cluster of elliptical objects for different cases of closely spaced, merging, and overlapping configurations. The results obtained by our analytical approach are validated with full-wave numerical simulations. PMID:25894518
Liu, Hongyu
2012-01-01
In this note, we present some interesting observations on the Schiffer's conjecture, interior transmission eigenvalue problem and their connections to singular and nonsingular invisibility cloaking problems of acoustic waves.
The scattering of a cylindrical invisibility cloak: reduced parameters and optimization
International Nuclear Information System (INIS)
We investigate the scattering of 2D cylindrical invisibility cloaks with simplified constitutive parameters with the assistance of scattering coefficients. We show that the scattering of the cloaks originates not only from the boundary conditions but also from the spatial variation of the component of permittivity/permeability. According to our formulation, we propose some restrictions to the invisibility cloak in order to minimize its scattering after the simplification has taken place. With our theoretical analysis, it is possible to design a simplified cloak using some peculiar composites such as photonic crystals which mimic an effective refractive index landscape rather than offering effective constitutives, meanwhile cancelling the scattering from the inner and outer boundaries.
The scattering of a cylindrical invisibility cloak: reduced parameters and optimization
Energy Technology Data Exchange (ETDEWEB)
Peng, L; Mortensen, N A [Department of Photonics Engineering, Technical University of Denmark, DTU-building 345 west, DK-2800 Kongens Lyngby (Denmark); Ran, L, E-mail: plia@fotonik.dtu.dk [Department of Information and Electronic Engineering, Zhejiang University, Hangzhou 310027 (China)
2011-04-06
We investigate the scattering of 2D cylindrical invisibility cloaks with simplified constitutive parameters with the assistance of scattering coefficients. We show that the scattering of the cloaks originates not only from the boundary conditions but also from the spatial variation of the component of permittivity/permeability. According to our formulation, we propose some restrictions to the invisibility cloak in order to minimize its scattering after the simplification has taken place. With our theoretical analysis, it is possible to design a simplified cloak using some peculiar composites such as photonic crystals which mimic an effective refractive index landscape rather than offering effective constitutives, meanwhile cancelling the scattering from the inner and outer boundaries.
Molding the flow of light with a magnetic field: plasmonic cloaking and directional scattering
Kort-Kamp, W J M; Pinheiro, F A; Farina, C
2014-01-01
We investigate electromagnetic scattering and plasmonic cloaking in a system composed by a dielectric cylinder coated with a magneto-optical shell. In the long-wavelength limit we demonstrate that the application of an external magnetic field can not only switch on and off the cloaking mechanism but also mitigate losses, as the absorption cross-section is shown to be minimal precisely at the cloaking operation frequency band. We also show that the angular distribution of the scattered radiation can be effectively controlled by applying an external magnetic field, allowing for a swift change in the scattering pattern. By demonstrating that these results are feasible with realistic, existing magneto-optical materials, such as graphene epitaxially grown on SiC, we suggest that magnetic fields could be used as an effective, versatile external agent to tune plasmonic cloaks and to dynamically control electromagnetic scattering in an unprecedented way, we hope that these results may find use in disruptive photonic ...
Zhou, Xiaoxia; Chen, Ying; Zhou, Yuan; Luo, Zhaoming
2016-04-01
We studied the electromagnetic scattering from cylindrical cloaks with a quantity of discrete homogeneous layers. The scattering cross sections (SCS) of electromagnetic cloaks designed by different coordinate transformation function are discussed by using a polynomial transform function. The results show that besides the inner boundary, the interfaces between the adjacent discrete anisotropic layers inside the cloak also affect its performance. Through the proper design of the coordinate transformation order, the electromagnetic field distribution insides the cloak can be optimized and the invisible performance of the cloak could be improved with minimization of SCS. These results provide a better way of designing the cloak to achieve low scattering with only a few layers of anisotropic metamaterials.
Li, Ying; Shen, Xiangying; Wu, Zuhui; Huang, Junying; Chen, Yixuan; Ni, Yushan; Huang, Jiping
2015-01-01
The macroscopic control of ubiquitous heat flow remains poorly explored due to the lack of a fundamental theoretical method. Here, by establishing temperature-dependent transformation thermotics for treating materials whose conductivity depends on temperature, we show analytical and simulation evidence for switchable thermal cloaking and a macroscopic thermal diode based on the cloaking. The latter allows heat flow in one direction but prohibits the flow in the opposite direction, which is al...
Design Method for Electromagnetic Cloak with Arbitrary Shapes Based on Laplace's Equation
Hu, Jin; Zhou, Xiaoming; Hu, Gengkai
2008-01-01
In transformation optics, the space transformation is viewed as the deformation of a material. The permittivity and permeability tensors in the transformed space are found to correlate with the deformation field of the material. By solving the Laplace's equation, which describes how the material will deform during a transformation, we can design electromagnetic cloaks with arbitrary shapes if the boundary conditions of the cloak are considered. As examples, the material parameters of the sphe...
Qiu, Cheng-Wei; Novitsky, Andrey V.; Ma, Hua; Qu, Shaobo
2009-01-01
An analytical method of electromagnetic wave interactions with a general radially anisotropic cloak is established. It is able to deal with arbitrary parameters ($\\epsilon_r(r)$, $\\mu_r(r)$, $\\epsilon_t(r)$ and $\\mu_t(r)$) of a radially anisotropic inhomogeneous shell. The general cloaking condition is proposed from the wave relations for the first time. We derive the parameters of a novel class of spherical nonlinear cloaks and examine its invisibility performance by the proposed method at v...
Active cloaking of resonant coated inclusions for waves in membranes and Kirchhoff plates
O'Neill, J; McPhedran, R C; Movchan, A B; Movchan, N V; Moggach, C Henderson
2015-01-01
The dynamic response of a coated inclusion is considered in the context of active cloaking. The active cloak is achieved for a coated inclusion in the presence of membrane and flexural waves. In this paper, we investigate the design of an active cloak for a coated inclusion in three frequency regimes: the very low frequency (monopole dominated) range, the intermediate range, and the higher frequency range in which scattering resonances occur. In the first of these ranges, we validate previous work, which resulted in a simple mass-compensation design for the monopole scatterer, while in the second and third ranges, a combination of the use of an appropriate coating and the appropriate choice of the amplitudes of the active cloaking sources is necessary. We show that such cloaking can indeed be effective in the region of strong scattering resonances. We give closed form analytic expressions for the required amplitudes of the active cloaking sources in the three frequency regions and provide asymptotic estimates...
Synthesis of vibration control and health monitoring of building structures under unknown excitation
International Nuclear Information System (INIS)
The vibration control and health monitoring of building structures have been actively investigated in recent years but often treated separately according to the primary objective pursued. In this study, a time-domain integrated vibration control and health monitoring approach is proposed based on the extended Kalman filter (EKF) for identifying the physical parameters of the controlled building structures without the knowledge of the external excitation. The physical parameters and state vectors of the building structure are then estimated and used for the determination of the control force for the purpose of the vibration attenuation. The interaction between the health monitoring and vibration control is revealed and assessed. The feasibility and reliability of the proposed approach is numerically demonstrated via a five-story shear building structure equipped with magneto-rheological (MR) dampers. Two types of excitations are considered: (1) the EI-Centro ground excitation underneath of the building and (2) a swept-frequency excitation applied on the top floor of the building. Results show that the structural parameters as well as the unknown dynamic loadings could be identified accurately; and, at the same time, the structural vibration is significantly reduced in the building structure. (paper)
Building Footprints - MO 2011 Montgomery Structure Footprints (SHP)
NSGIC GIS Inventory (aka Ramona) — Missouri Structure Footprints are structure footprints generated as polygons from a two pass look over the 2007 State 2ft imagery. Unlike the structure points, the...
Building Footprints - MO 2011 Lincoln Structure Footprints (SHP)
NSGIC GIS Inventory (aka Ramona) — Missouri Structure Footprints are structure footprints generated as polygons from a two pass look over the 2007 State 2ft imagery. Unlike the structure points, the...
Building Footprints - MO 2011 Warren Structure Footprints (SHP)
NSGIC GIS Inventory (aka Ramona) — Missouri Structure Footprints are structure footprints generated as polygons from a two pass look over the 2007 State 2ft imagery. Unlike the structure points, the...
Magnetization of Steel Building Materials and Structures in the Natural Geomagnetic Field
Directory of Open Access Journals (Sweden)
E. Čermáková
2005-01-01
Full Text Available This paper presents the physical basis of the magnetic properties of ferromagnetic materials and shows their relationships with external geomagnetic field. It graphically processes the experimental data detected by an HMR magnetometer. Taking into account the natural geomagnetic field under the effects of steel U profiles, variations of the natural geomagnetic field in a steel structure building are indicated and the potential existence of Sick Building Syndrome (SBS in these types of buildings is pointed out.
2014-01-01
This study aims to present an efficient plan for the application of a geothermal energy facility at the building structure planning phase. Energy consumption, energy cost and the primary energy consumption of buildings were calculated to enable a comparison of buildings prior to the application of a geothermal energy facility. The capacity for energy savings and the costs related to the installation of such a facility were estimated. To obtain more reliable criteria for economic feasibility, ...
Vibrations in a Multi-Storey Lightweight Building Structure
DEFF Research Database (Denmark)
Andersen, Lars Vabbersgaard; Kirkegaard, Poul Henning
2013-01-01
This paper provides a quantification of the changes in vibration level that can be expected in a lightweight multi-storey wooden building due to reduced connection stiffness or added nonstructural mass. Firstly, the impact of changes in the floor-to-wall connections is examined. Secondly, a study...
A cost effective wireless structural health monitoring network for buildings in earthquake zones
International Nuclear Information System (INIS)
The design, programming and implementation of a cost effective wireless structural health monitoring system (wSHMs) is presented, able to monitor the seismic and/or man-made acceleration in buildings. This system actually operates as a sensor network exploiting internet connections that commonly exist, aiming to monitor the structural health of the buildings being installed. Key-feature of wSHMs is that it can be implemented in Wide Area Network mode to cover many remote structures and buildings, on metropolitan scale. Acceleration data is able to send, in real time, from dozens of buildings of a broad metropolitan area, to a central database, where they are analyzed in order to depict possible structural damages or nonlinear characteristics and alert for non-appropriateness of specific structures. (paper)
Cyclic concentrator, carpet cloaks and fisheye lens via transformation plasmonics
Alaoui, M.; Rustomji, K.; Chang, T. M.; Tayeb, G.; Sabouroux, P.; Quidant, R.; Enoch, S.; Guenneau, S.; Abdeddaim, R.
2016-04-01
We first review basic equations of plasmonics in anisotropic media. We recall the origin of Maxwell’s gradient index fisheye lens. We then apply tools of transformation optics to the design of a cyclic concentrator and a variety of plasmonic carpet-cloaks. We further give a brief account of the discovery of spoof plasmon polaritons (SfPPs) by Pendry et al (2004 Science 305 847–8) 150 years after Maxwell invented the fisheye lens. Finally, we experimentally demonstrate a concept of a fisheye lens for SfPPs at microwave frequencies. We stress that perfect metal surfaces perforated with dielectrics offer a playground for moulding surface waves in many areas of physics.
International Nuclear Information System (INIS)
In conventional dynamic structural analyses for determining dynamic system response for various locations at which components are installed inside the structures it is common practice (in order to simplify analytical effort) to assume that the anchorage (anchor plate, anchor bolts or throughbolts, concrete and reinforcement in the area of bound) has rigid body characteristics and that the building structure itself does not display any local response of its own. The influence of the stiffness of the anchor plate as well anchor bolts and its stress level on the dynamic response is also neglected. For a large number of anchoring systems, especially for all those components and systems having only a small mass, this assumption is certainly appropriate. At some locations, particularly at points where heavy components are anchored or when loading input has been increased, this can lead to local loading of the anchor system as well as of the building structure well into the nonlinear range. Often, verification of capability to accommodate these loads is not possible without changing the wall thicknesses or increasing the percentage of reinforcement. Since the presence of linear or nonlinear effects can be expected to result in energy dissipation (increase in damping capacity and also a change in the stiffness of the coupled system) it must be assumed that the dynamic response between the theoretical coupling point A and the real connection point B of the component on the anchor plate can be considerably altered. Some changes of the dynamic response in the connection point B have to be expected generally even in cases of linear-elastic loading of the anchorage. Using typical anchoring systems as an example, the influence of consideration of nonlinear effects in the anchorage area of a typical anchor plate on the dynamic response as well as the conservatism of conventional analytical approaches are investigated
VIBRATION OF FRAME BUILDING STRUCTURES CAUSED BY UNDERGROUND TRAINS
Directory of Open Access Journals (Sweden)
P. V. Аliavdin
2011-01-01
Full Text Available The paper contains investigations on element vibration of a real residential 9-storeyed reinforced-concrete frame building induced by train movement in the shallow subway. A design model for a problem on propagation of bending waves within the limits of the typical fragment of a skeleton is presented in the paper. The steady state vibrations of a column and reinforced-concrete slab induced by an excited force which is equivalent to the impact of the subway trains have been investigated in the paper. The problem has been solved numerically on the basis of the ANSYS FEA program. Numerical results have been compared with an approximate analytical solution and data on full-scale experiment. A prediction technique for vibration propagation in the designed buildings is offered in the paper.
Cooling of the Building Structure by Night-time Ventilation
DEFF Research Database (Denmark)
Artmann, Nikolai
In modern, extensively glazed office buildings, due to high solar and internal loads and increased comfort expectations, air conditioning is increasingly applied even in moderate and cold climates, like in Central and Northern Europe. Particularly in these cases, night-time ventilation is often...... seen as a promising passive cooling concept. Many successful examples of passively cooled buildings demonstrate the possibility of providing good thermal comfort conditions without the need for energy-intensive air conditioning systems. However, due to uncertainties in the prediction of thermal comfort......-time ventilation alone might not be sufficient to guarantee thermal comfort. Possible time-dependent changes in CCP were assessed for the period 1990-2100, with particular emphasis on the Intergovernmental Panel on Climate Change (IPCC) "A2" and "B2" scenarios for future emissions of greenhouse gases and aerosols...
Ethical Guidelines for Structural Interventions to Small-Scale Historic Stone Masonry Buildings.
Hurol, Yonca; Yüceer, Hülya; Başarır, Hacer
2015-12-01
Structural interventions to historic stone masonry buildings require that both structural and heritage values be considered simultaneously. The absence of one of these value systems in implementation can be regarded as an unethical professional action. The research objective of this article is to prepare a guideline for ensuring ethical structural interventions to small-scale stone historic masonry buildings in the conservation areas of Northern Cyprus. The methodology covers an analysis of internationally accepted conservation documents and national laws related to the conservation of historic buildings, an analysis of building codes, especially Turkish building codes, which have been used in Northern Cyprus, and an analysis of the structural interventions introduced to a significant historic building in a semi-intact state in the walled city of Famagusta. This guideline covers issues related to whether buildings are intact or ruined, the presence of earthquake risk, the types of structural decisions in an architectural conservation project, and the values to consider during the decision making phase. PMID:25524322
I. F. Fialko; A. S. Statsenko
2014-01-01
The paper considers power-efficient systems applied for heating building and structure external walls with ventilated air spaces and prescribes directions and problems pertaining to power-efficiency improvement of such systems.
Dhakal, Rajesh P.; Pourali, Atefeh; Tasligedik, Ali Sahin; Yeow, Trevor; Baird, Andrew; MacRae, Gregory; Pampanin, Stefano; Palermo, Alessandro
2016-03-01
This paper summarizes the research on non-structural elements and building contents being conducted at University of Canterbury in New Zealand. Since the 2010-2011 series of Canterbury earthquakes, in which damage to non-structural components and contents contributed heavily to downtime and overall financial loss, attention to seismic performance and design of non-structural components and contents in buildings has increased exponentially in NZ. This has resulted in an increased allocation of resources to research leading to development of more resilient non-structural systems in buildings that would incur substantially less damage and cause little downtime during earthquakes. In the last few years, NZ researchers have made important developments in understanding and improving the seismic performance of secondary building elements such as partitions, facades, ceilings and contents.
Seismic soil-structure interaction in buildings. I: Analytical aspects
Stewart, Jonathan P.; Fenves, Gregory L.; Seed, Raymond B
1999-01-01
Recent improvements in seismological source modeling, analysis of travel path effects, and characterization of local site effects on strong shaking have led to significant advances in both code-based and more advanced procedures for evaluating seismic demand for structural design. A missing link, however, has been an improved and empirically verified treatment of soil-structure interaction (SSI) effects on both the strong motions transmitted to structures and the structural response to these ...
Energy Technology Data Exchange (ETDEWEB)
Naito, Yukio [Kajima Corp., Kajima Technical Research Institute, Tokyo (Japan); Yano, Tatsuo [Kajima Corp., Nuclear Power Department, Tokyo (Japan); Iguchi, Michio [Science Univ. of Tokyo, Faculty of Science and Technology, Noda, Chiba (Japan); Kitada, Yoshio [Nuclear Power Engineering Corp., Tokyo (Japan)
2003-02-01
High-rigidity and heavy buildings such as reactor buildings usually have large soil-structure interaction effect in its dynamic response. In such cases, spectrum ratio of the top of the building to the bottom for horizontal motion gives different result from the dynamic characteristics of the building under fixed-base condition because the effect of the rocking motion of the base is not eliminated. This paper presented a new method for such problems; applied it to a ground blast vibration, microtremors and forced vibration test results; and transfer functions of the building for fixed-base condition were obtained. The proposed method can be applied when the exciter is set at the upper part of the buildings. (author)
International Nuclear Information System (INIS)
High-rigidity and heavy buildings such as reactor buildings usually have large soil-structure interaction effect in its dynamic response. In such cases, spectrum ratio of the top of the building to the bottom for horizontal motion gives different result from the dynamic characteristics of the building under fixed-base condition because the effect of the rocking motion of the base is not eliminated. This paper presented a new method for such problems; applied it to a ground blast vibration, microtremors and forced vibration test results; and transfer functions of the building for fixed-base condition were obtained. The proposed method can be applied when the exciter is set at the upper part of the buildings. (author)
Sangyong Kim; Joon-Ho Moon; Yoonseok Shin; Gwang-Hee Kim; Deok-Seok Seo
2013-01-01
The objective of this research is to quantitatively measure and compare the environmental load and construction cost of different structural frame types. Construction cost also accounts for the costs of CO2 emissions of input materials. The choice of structural frame type is a major consideration in construction, as this element represents about 33% of total building construction costs. In this research, four constructed buildings were analyzed, with these having either reinforced concrete (R...
The dynamic responses of the soil-auxiliary buildings structure interaction system
International Nuclear Information System (INIS)
The dynamic responses of the soil-auxiliary buildings structure interaction system in the nuclear power plant are concerned. The main distinguished feature of this study is that the extreme un-symmetry of the auxiliary buildings and reactor containment are considered. A Synthetical mechanical model for study is established. Finally, the analysis of the dynamic response of the Qinshan Nuclear Power Plant structure is taken as a simple example of applying this method and the numerical results are given
ÇELEBİ, Erkan
2005-01-01
In this paper, a simplified methodology of analysis for the seismic response of 3-dimensional irregular high-rise buildings on a rigid footing resting on the surface of a linear elastic half-space is formulated. An efficient method using modal decomposition and carried out in the frequency domain by using the fast Fourier transform to obtain the structural response of torsionally asymmetric buildings, including soil-structure interaction effects, is presented. Applying this algorithm...
Composite structures of steel and concrete beams, slabs, columns, and frames for buildings
Johnson, R P
2008-01-01
This book sets out the basic principles of composite construction with reference to beams, slabs, columns and frames, and their applications to building structures. It deals with the problems likely to arise in the design of composite members in buildings, and relates basic theory to the design approach of Eurocodes 2, 3 and 4.The new edition is based for the first time on the finalised Eurocode for steel/concrete composite structures.
The integration of water loop heat pump and building structural thermal storage systems
Energy Technology Data Exchange (ETDEWEB)
Marseille, T.J.; Schliesing, J.S.
1991-10-01
Many commercial buildings need heat in one part and, at the same time, cooling in another part. Even more common is the need for heating during one part of the day and cooling during another in the same spaces. If that energy could be shifted or stored for later use, significant energy might be saved. If a building's heating and cooling subsystems could be integrated with the building's structural mass and used to collect, store, and deliver energy, the energy might be save cost-effectively. To explore this opportunity, researchers at the Pacific Northwest Laboratory (PNL) examined the thermal interactions between the heating, ventilating, and air-conditioning (HVAC) system and the structure of a commercial building. Computer models were developed to simulate the interactions in an existing building located in Seattle, Washington, to determine how these building subsystems could be integrated to improve energy efficiency. The HVAC subsystems in the existing building were modeled. These subsystems consist of decentralized water-source heat pumps (WSHP) in a closed water loop, connected to cooling towers for heat rejection during cooling mode and boilers to augment heating. An initial base case'' computer model of the Seattle building, as-built, was developed. Metered data available for the building were used to calibrate this model to ensure that the analysis would provide information that closely reflected the operation of a real building. The HVAC system and building structure were integrated in the model using the concrete floor slabs as thermal storage media. The slabs may be actively charged during off-peak periods with the chilled water in the loop and then either actively or passively discharged into the conditioned space during peak periods. 21 refs., 37 figs., 17 tabs.
Design of load-bearing structure of an office building in Kranj
Possnig, Luka
2012-01-01
This thesis presents static analysis of load-bearing structure of a three storey office building in Kranj according to current Eurocode standards. The load-bearing structure is made of reinforced concrete and consists of monolith roof and storey plates, brick walls, beams and columns. In the analysis of the structure all impacts, that may influence the structure in its lifecycle are considered. The analysis of the plates was performed with a commercial program SAP2000 (Computers and Structure...
Institute of Scientific and Technical Information of China (English)
Zhijun LI; Zichen DENG
2009-01-01
In this paper, a novel "composite reaching law" was explained in details: 1) the equation of discrete motion for a control system; 2) the design of discrete-time variable structure control. In addition, the model of a three-storey shear-type building structure was used to verify the effectiveness of the discrete variable structure control method. The results of numerical example analysis of the model show that the control law can effectively reduce the peak value of seismic response of the building structure and the chattering effect of the control system.
HYPERSTATIC STRUCTURE MAPPING MODEL BUILDING AND OPTIMIZING DESIGN
Institute of Scientific and Technical Information of China (English)
XU Gening; GAO Youshan; ZHANG Xueliang; YANG Ruigang
2007-01-01
Hyperstatic structure plane model being built by structural mechanics is studied. Space model precisely reflected in real stress of the structure is built by finite element method (FEM) analysis commerce software. Mapping model of complex structure system is set up, with convenient calculation just as in plane model and comprehensive information as in space model. Plane model and space model are calculated under the same working condition. Plane model modular construction inner force is considered as input data; Space model modular construction inner force is considered as output data. Thus specimen is built on input data and output data. Character and affiliation are extracted through training specimen, with the employment of nonlinear mapping capability of the artificial neural network. Mapping model with interpolation and extrapolation is gained, laying the foundation for optimum design. The steel structure of high-layer parking system (SSHLPS) is calculated as an instance. A three-layer back-propagation (BP) net including one hidden layer is constructed with nine input nodes and eight output nodes for a five-layer SSHLPS. The three-layer structure optimization result through the mapping model interpolation contrasts with integrity re-analysis, and seven layers structure through the mapping model extrapolation contrasts with integrity re-analysis. Any layer SSHLPS among 1～8 can be calculated with much accuracy. Amount of calculation can also be reduced if it is applied into the same topological structure, with reduced distortion and assured precision.
Building Knowledge Structures in Teaching Cross-Cultural Sales Genres.
Yunxia, Zhu
2000-01-01
Considers how approaching genres as knowledge structures provides a useful theoretical basis for teaching students to communicate across cultures. Presents an approach that is divided into four interrelated teaching stages: background information, communicative purposes, text structure, and the implications of genre comparisons. Finds teaching the…
Energy evaluation of urban structure and dimensioning of building site using iso-shadow method
Energy Technology Data Exchange (ETDEWEB)
Kristl, Z.; Krainer, A. [Ljubljana Univ., Faculty of Civil and Geodetic Engineering, Ljubljana (Slovenia)
2001-07-01
The paper presents the energy evaluation of urban structures and the dimensioning of building sites using the iso-shadow method. Iso-shadows represent the ratio of incident solar radiation on a building or land to unobstructed solar radiation received at the same location during the chosen period to time, day or year, respectively. This method enables quantitative evaluation of energy efficiency of the selected layout organisations. For the calculation of thermal flow the computer tool 'SENCE' (SHADOWS), developed at the Faculty of Civil and Geodetic Engineering at the University of Ljubljana, was used. Various building structures were investigated. First a building with reference floor geometry (length 60 m, width 12 m, height 6 m) was simulated. The site layout consisting of four parallel reference buildings was designed, taking into account the chosen minimum duration of solar radiation during the year, calculated with the iso-shadows module of the 'SENCE' programme. Then the building width was increased to 24 m and 36 m, respectively. Also the building height was varied in three steps, 6 m, 12 m and 18 m. The results of the simulations are presented in the form of iso-shadows charts. The comparison between various building types was made, taking into account: modified orientations, monitored density of residents and changed site size due to different building types. The evaluation of the results was carried out and the advantages and disadvantages of various building types are discussed. It was found that building width and height substantially influence the required site size, site layout and resident density. (Author)
X-ray and back-wall echo ultrasonic examination of wrought iron building structures
Directory of Open Access Journals (Sweden)
Vidovszky István
2008-01-01
Full Text Available The wrought iron building structures constituting part of the architectural heritage, e. g. handrails, gate hinges, columns, arch ties and wall ties represent incorporeal value, but operate as load bearing structures as well. There are few information on their mechanical properties and quality. Due to the inhomogeneity of the material of wrought iron building structures generated during the production, the known metal testing methods, as the tensile and hardness tests or metallographic examination, are not enough to survey the properties of such structures in depth. For the further and more accurate examinations, the application of X-ray and back-wall echo ultrasonic tests are essential. The goal of our paper is the presentation of the application of the examinations used extensively in the machine industry for the testing of wrought iron building structures.
Effect of Soft Story on Structural Response of High Rise Buildings
Energy Technology Data Exchange (ETDEWEB)
Hejazi, F; Jilani, S; Noorzaei, J; Chieng, C Y; Jaafar, M S; Ali, A A Abang, E-mail: jamal@eng.upm.edu.my [Department of Civil, Engineering faculty, University Putra Malaysia, 43300 Serdang, Selangor (Malaysia)
2011-02-15
Severe structural damage suffered by several modern buildings during recent earthquakes illustrates the importance of avoiding sudden changes in lateral stiffness and strength. Recent earthquakes that occurred have shown that a large number of existing reinforced concrete buildings are vulnerable to damage or even collapse during a strong earthquake. While damage and collapse due to soft story are most often observed in buildings, they can also be developed in other types of structures. The lower level containing the concrete columns behaved as a soft story in that the columns were unable to provide adequate shear resistance during the earthquake. Usually the most economical way of retrofitting such as a building is by adding proper bracing to soft stories. So, in this paper occurring of soft at the lower level of high rise buildings subjected to earthquake has been studied. Also has been tired to investigate on adding of bracing in various arrangements to structure in order to reduce soft story effect on seismic response of building. It is lead to assess the vulnerability level of existing multi-storied buildings so that they can be retrofitted to possess the minimum requirements. This will help in minimizing the impending damages and catastrophes.
Building Points - MO 2014 Crawford Structure Points (SHP)
NSGIC GIS Inventory (aka Ramona) — Staff at the Geographic Resources Center placed attributed points on all roofed structures visible at a scale of 1:2000 using MSDIS-DOQQ 2008 2-foot aerial imagery...
Building Points - MO 2014 Clinton Structure Points (SHP)
NSGIC GIS Inventory (aka Ramona) — Staff at the Geographic Resources Center placed attributed points on all roofed structures visible at a scale of 1:2000 using MSDIS-DOQQ 2008 2-foot aerial imagery...
Building Points - MO 2014 Atchison Structure Points (SHP)
NSGIC GIS Inventory (aka Ramona) — Staff at the Geographic Resources Center placed attributed points on all roofed structures visible at a scale of 1:2000 using MSDIS-DOQQ 2008 2-foot aerial imagery...
Building Points - MO 2014 Carroll Structure Points (SHP)
NSGIC GIS Inventory (aka Ramona) — Staff at the Geographic Resources Center placed attributed points on all roofed structures visible at a scale of 1:2000 using MSDIS-DOQQ 2008 2-foot aerial imagery...
Building Points - MO 2014 Buchanan Structure Points (SHP)
NSGIC GIS Inventory (aka Ramona) — Staff at the Geographic Resources Center placed attributed points on all roofed structures visible at a scale of 1:2000 using MSDIS-DOQQ 2008 2-foot aerial imagery...
Building Points - MO 2014 Dade Structure Points (SHP)
NSGIC GIS Inventory (aka Ramona) — Staff at the Geographic Resources Center placed attributed points on all roofed structures visible at a scale of 1:2000 using MSDIS-DOQQ 2008 2-foot aerial imagery...
Building Points - MO 2014 Camden Structure Points (SHP)
NSGIC GIS Inventory (aka Ramona) — Staff at the Geographic Resources Center placed attributed points on all roofed structures visible at a scale of 1:2000 using MSDIS-DOQQ 2008 2-foot aerial imagery...
Building Points - MO 2014 Caldwell Structure Points (SHP)
NSGIC GIS Inventory (aka Ramona) — Staff at the Geographic Resources Center placed attributed points on all roofed structures visible at a scale of 1:2000 using MSDIS-DOQQ 2008 2-foot aerial imagery...
Building Points - MO 2014 Cedar Structure Points (SHP)
NSGIC GIS Inventory (aka Ramona) — Staff at the Geographic Resources Center placed attributed points on all roofed structures visible at a scale of 1:2000 using MSDIS-DOQQ 2008 2-foot aerial imagery...
Building Points - MO 2014 Clay Structure Points (SHP)
NSGIC GIS Inventory (aka Ramona) — Staff at the Geographic Resources Center placed attributed points on all roofed structures visible at a scale of 1:2000 using MSDIS-DOQQ 2008 2-foot aerial imagery...
Building Points - MO 2014 Butler Structure Points (SHP)
NSGIC GIS Inventory (aka Ramona) — Staff at the Geographic Resources Center placed attributed points on all roofed structures visible at a scale of 1:2000 using MSDIS-DOQQ 2008 2-foot aerial imagery...
Building Points - MO 2014 Christian Structure Points (SHP)
NSGIC GIS Inventory (aka Ramona) — Staff at the Geographic Resources Center placed attributed points on all roofed structures visible at a scale of 1:2000 using MSDIS-DOQQ 2008 2-foot aerial imagery...
Building Points - MO 2014 Barry Structure Points (SHP)
NSGIC GIS Inventory (aka Ramona) — Staff at the Geographic Resources Center placed attributed points on all roofed structures visible at a scale of 1:2000 using MSDIS-DOQQ 2008 2-foot aerial imagery...
Building Points - MO 2014 Chariton Structure Points (SHP)
NSGIC GIS Inventory (aka Ramona) — Staff at the Geographic Resources Center placed attributed points on all roofed structures visible at a scale of 1:2000 using MSDIS-DOQQ 2008 2-foot aerial imagery...
Building Points - MO 2014 Dallas Structure Points (SHP)
NSGIC GIS Inventory (aka Ramona) — Staff at the Geographic Resources Center placed attributed points on all roofed structures visible at a scale of 1:2000 using MSDIS-DOQQ 2008 2-foot aerial imagery...
Building Points - MO 2014 Daviess Structure Points (SHP)
NSGIC GIS Inventory (aka Ramona) — Staff at the Geographic Resources Center placed attributed points on all roofed structures visible at a scale of 1:2000 using MSDIS-DOQQ 2008 2-foot aerial imagery...
Building Points - MO 2014 Audrain Structure Points (SHP)
NSGIC GIS Inventory (aka Ramona) — Staff at the Geographic Resources Center placed attributed points on all roofed structures visible at a scale of 1:2000 using MSDIS-DOQQ 2008 2-foot aerial imagery...
Building Points - MO 2014 Adair Structure Points (SHP)
NSGIC GIS Inventory (aka Ramona) — Staff at the Geographic Resources Center placed attributed points on all roofed structures visible at a scale of 1:2000 using MSDIS-DOQQ 2008 2-foot aerial imagery...
Building Points - MO 2014 Bates Structure Points (SHP)
NSGIC GIS Inventory (aka Ramona) — Staff at the Geographic Resources Center placed attributed points on all roofed structures visible at a scale of 1:2000 using MSDIS-DOQQ 2008 2-foot aerial imagery...
Building Points - MO 2014 Clark Structure Points (SHP)
NSGIC GIS Inventory (aka Ramona) — Staff at the Geographic Resources Center placed attributed points on all roofed structures visible at a scale of 1:2000 using MSDIS-DOQQ 2008 2-foot aerial imagery...
Building Points - MO 2014 Benton Structure Points (SHP)
NSGIC GIS Inventory (aka Ramona) — Staff at the Geographic Resources Center placed attributed points on all roofed structures visible at a scale of 1:2000 using MSDIS-DOQQ 2008 2-foot aerial imagery...
Building Points - MO 2014 Cass Structure Points (SHP)
NSGIC GIS Inventory (aka Ramona) — Staff at the Geographic Resources Center placed attributed points on all roofed structures visible at a scale of 1:2000 using MSDIS-DOQQ 2008 2-foot aerial imagery...
Building Points - MO 2014 Barton Structure Points (SHP)
NSGIC GIS Inventory (aka Ramona) — Staff at the Geographic Resources Center placed attributed points on all roofed structures visible at a scale of 1:2000 using MSDIS-DOQQ 2008 2-foot aerial imagery...
Building Points - MO 2014 Andrew Structure Points (SHP)
NSGIC GIS Inventory (aka Ramona) — Staff at the Geographic Resources Center placed attributed points on all roofed structures visible at a scale of 1:2000 using MSDIS-DOQQ 2008 2-foot aerial imagery...
Building Points - MO 2012 Perry Structure Points (SHP)
NSGIC GIS Inventory (aka Ramona) — Staff at the Geographic Resources Center placed categorized points on all roofed structures visible at a scale of 1:2000 using MSDIS-DOQQ 2008 2-foot aerial imagery...
Building Points - MO 2014 Carter Structure Points (SHP)
NSGIC GIS Inventory (aka Ramona) — Staff at the Geographic Resources Center placed attributed points on all roofed structures visible at a scale of 1:2000 using MSDIS-DOQQ 2008 2-foot aerial imagery...
Building Points - MO 2012 Bollinger Structure Points (SHP)
NSGIC GIS Inventory (aka Ramona) — Staff at the Geographic Resources Center placed categorized points on all roofed structures visible at a scale of 1:2000 using MSDIS-DOQQ 2008 2-foot aerial imagery...
Building Points - MO 2011 Lincoln Structure Points (SHP)
NSGIC GIS Inventory (aka Ramona) — MSDIS staff identified and located all ?binary? structures and compiled them into a spatial database. Annual review and maintenance of the database will occur with...
Building Points - MO 2012 Iron Structure Points (SHP)
NSGIC GIS Inventory (aka Ramona) — Staff at the Geographic Resources Center placed categorized points on all roofed structures visible at a scale of 1:2000 using MSDIS-DOQQ 2008 2-foot aerial imagery...
Building Points - MO 2012 Madison Structure Points (SHP)
NSGIC GIS Inventory (aka Ramona) — Staff at the Geographic Resources Center placed categorized points on all roofed structures visible at a scale of 1:2000 using MSDIS-DOQQ 2008 2-foot aerial imagery...
Building Points - MO 2011 Montgomery Structure Points (SHP)
NSGIC GIS Inventory (aka Ramona) — MSDIS staff identified and located all ?binary? structures and compiled them into a spatial database. Annual review and maintenance of the database will occur with...
Building Points - MO 2011 Warren Structure Points (SHP)
NSGIC GIS Inventory (aka Ramona) — MSDIS staff identified and located all ?binary? structures and compiled them into a spatial database. Annual review and maintenance of the database will occur with...
Building Points - MO 2012 Cape Girardeau Structure Points (SHP)
NSGIC GIS Inventory (aka Ramona) — Staff at the Geographic Resources Center placed categorized points on all roofed structures visible at a scale of 1:2000 using MSDIS-DOQQ 2008 2-foot aerial imagery...
Building Points - MO 2012 St. Genevieve Structure Points (SHP)
NSGIC GIS Inventory (aka Ramona) — Staff at the Geographic Resources Center placed categorized points on all roofed structures visible at a scale of 1:2000 using MSDIS-DOQQ 2008 2-foot aerial imagery...
Building Points - MO 2012 Revised Boone Structure Points (SHP)
NSGIC GIS Inventory (aka Ramona) — MSDIS staff provided project management and worked with the Mid-MO RPC to locate "structures" within their region. MSDIS staff identified and located all “binary”...
Building Points - MO 2012 St. Francois Structure Points (SHP)
NSGIC GIS Inventory (aka Ramona) — Staff at the Geographic Resources Center placed categorized points on all roofed structures visible at a scale of 1:2000 using MSDIS-DOQQ 2008 2-foot aerial imagery...
Farhat, Mohamed; Guenneau, Sebastien; Enoch, Stefan
2012-01-01
A cylindrical cloak is designed to control the bending waves propagating in isotropic thin plates. This is achieved through homogenization of a multiply perforated coating of isotropic homogeneous elastic material, which greatly simplifies the design of the multilayered cloak we proposed [Phys. Rev. Lett.PRLTAO0031-900710.1103/PhysRevLett.103.024301 103, 024301 (2009)]. We first derive the homogenized biharmonic equation, which involves an anisotropic Young's modulus and an isotropic mass density. We then numerically show that a clamped obstacle is cloaked over a finite range of frequencies for an acoustic source located a couple of wavelengths away from its surrounding cloak. The reduced backward and forward scattering is confirmed by both the profile of the total field computed along a line passing through the source and the center of the cloak (near field confirmation), and the computation of the scattered far field.
Magnetization loop modelling for superconducting/ferromagnetic tube of an ac magnetic cloak
International Nuclear Information System (INIS)
From the combination of superconducting (SC) and ferromagnetic (FM) materials, one can prepare composites with unusual magnetic properties, e.g. for the cloaking of a dc or low-frequency ac magnetic field by a shell from a SC/FM composite. In the design and optimisation of such SC/FM structures, numerical modelling is essential. Non-linear magnetic permeability, as well as the hysteresis of both kinds of materials, are to be incorporated in the calculations aimed at achieving reliable estimates. We present a technique that allows the prediction of the ac magnetization loops of SC/FM composites. The critical state model-based approach is used to describe the properties of the superconducting material. The ferromagnetic part is characterized by its (non-hysteretic) nonlinear permeability. With these ingredients, the distributions of the magnetic field are calculated in subsequent instants of the ac cycle and are used to evaluate the preliminary data for the magnetization loop, which is still missing the hysteresis of the FM part. Afterward, the latter component is added to the magnetization loop by an approximation deduced from the known dependence of the hysteresis loss in the FM material on the ac magnetic field. In spite of its approximate nature, this approach demonstrated very good predictability in experimental tests. (paper)
International Nuclear Information System (INIS)
Seismic response at foundation of large building caused by strong ground motion has tendency to be less intense than corresponding free-field motion, especially in high frequency range. To explain this phenomenon and to apply it to practical soil-structure interaction (SSI) analysis, concept of wave incoherence (or spatial variation) was introduced. The spatial variation of ground motion can be quantified by coherency function, and several coherency functions have been developed for engineering purpose. However, there is little investigation about their application to SSI analysis and design for buildings influenced by adjacent structures. This paper is focused on the seismic response of a building whose foundation lies between those of nearby structures. Specifically, a tower building consisting of steel and concrete is modeled, and the building is assumed to be located on rock media. Analyses are categorized into four cases according to the type of foundation and the existence of adjacent structures. For each case, the results from incoherent SSI analysis are compared with those from coherent analysis to investigate the effect on the seismic response of the building
Optimization of time-delayed feedback control of seismically excited building structures
Institute of Scientific and Technical Information of China (English)
Xue-ping LI; Wei-qiu ZHU; Zu-guang YING
2008-01-01
An optimization method for time-delayed feedback control of partially observable linear building structures subjected to seismic excitation is proposed. A time-delayed control problem of partially observable linear building structure under horizontal ground acceleration excitation is formulated and converted into that of completely observable linear structure by using separation principle. The time-delayed control forces are approximately expressed in terms of control forces without time delay. The control system is then governed by Ito stochastic differential equations for the conditional means of system states and then transformed into those for the conditional means of modal energies by using the stochastic averaging method for quasi-Hamiltonian systems. The control law is assumed to be modal velocity feedback control with time delay and the unknown control gains are determined by the modal performance indices. A three-storey building structure is taken as example to illustrate the proposal method and the numerical results are confirmed by using Monte Carlo simulation.
Quick assessment tool for assurance of structural safety in the building process
Terwel, K.C.; Jansen, S.J.T.
2014-01-01
From forensic investigation it is known that many structural failures can be attributed to human errors and organizational factors. To provide project leaders with information on the current state of factors in the building process influencing structural safety, we developed a quick assessment tool.
Seismic testing of models and fragments of seismic isolated structures of NPS buildings
International Nuclear Information System (INIS)
This report states the bases of original methodology and results of model and full-scale seismic testing on 3-component seismic platforms (load-carrying capacity up to 500 t). For simulation of loads and shakes of elements of structures of seismic isolated buildings on the structure of the stands the technology of buried underground explosions was used. (author). 3 figs., 2 tabs
Enríquez-Zárate, J.; Silva-Navarro, G.; Abundis-Fong, H. F.
2016-05-01
This work deals with the structural and dynamic analysis of a building-like structure consisting of a three-story building with one active vibration absorber. The base of the structure is perturbed using an electromagnetic shaker, which provides forces with a wide range of excitation frequencies, including some resonance frequencies of the structure. One beam-column of the structure is coupled with a PZT stack actuator to reduce the vibrations. The overall mechanical structure is modeled using Euler-Lagrange methodology and validated using experimental modal analysis and Fine Element Method (FEM) techniques. The active control laws are synthesized to actively attenuate the vibration system response via the PZT stack actuator, caused by excitation forces acting on the base of the structure. The control scheme is obtained using Positive Acceleration Feedback (PAF) and Multiple Positive Acceleration Feedback (MPAF) to improve the closed-loop system response. Some experimental results are included to illustrate the overall system performance.
Hydraulic behaviour of a representative structural volume for containment buildings
International Nuclear Information System (INIS)
This contribution presents a simplified hydro mechanical approach for the study of sensitive structures like containment vessels of nuclear power plants. It is based on the calculation of permeability from two independent preliminary computations (drying and mechanical effects). The resulting distribution of the transfer property is then included in a hydraulic simulation to represent the consequences of a mechanical degradation on a gas pressure gradient simulation. Contrary to fully coupled methods which require a large number of parameters and heavy computational resources, this technique is suitable for large scale structural applications. The method is applied on a FE Representative Structural Volume model of a typical 1300 MWe prestressed containment vessel (PPCV) representative of the Electricite de France French power plants. It incorporates almost all components of the real structure with concrete, vertical and horizontal reinforcement bars, transverse reinforcements and prestressed tendons in both horizontal and vertical directions. The effect of damage localization on the hydraulic regime is investigated and an indicator based on the radial flow is developed to locate the zones where the leakage rate may be critical. (authors)
Influence of dynamic soil-structure interaction on building response to ground vibration
DEFF Research Database (Denmark)
Andersen, Lars Vabbersgaard
2014-01-01
Vibration from traffic and pile driving are an increasing problem in densely populated areas. To assess vibration levels in new or existing buildings near construction sites, roads or railways in the design phase, valid models for prediction of wave transmission via the ground and into a building......—this assumption makes sense. For this purpose, models with and without soil–structure interaction are compared for a variety of cases with respect to soil conditions, construction material and presence of a cellar under the building....
Expansion of core melt within the concrete foundation - effects on the reactor building structure
International Nuclear Information System (INIS)
The effects of core melt expanding in the concrete fundament of underground-situated nuclear power plants on the structure of the reactor building have been investigated. The radial reduction of the foundation plate is not to exceed 12 m, in case limited additional internal pressure loads of more than 6 bar are to be covered. Greater reductions will endanger the stability of the building. For the assumed load cases, no penetrating cracks will occur. During the subject test, the limiting walls of the building remained leak-proof up to an internal pressure of 2.5 bar. (orig.)
Energy Technology Data Exchange (ETDEWEB)
Marseille, T.J.; Johnson, B.K.; Wallin, R.P.; Chiu, S.A.; Crawley, D.B.
1989-01-01
This report is one in a series of reports describing research activities in support of the US Department of Energy (DOE) Commercial Building System Integration Research Program. The goal of the program is to develop the scientific and technical basis for improving integrated decision-making during design and construction. Improved decision-making could significantly reduce buildings' energy use by the year 2010. The objectives of the Commercial Building System Integration Research Program are: to identify and quantify the most significant energy-related interactions among building subsystems; to develop the scientific and technical basis for improving energy related interactions in building subsystems; and to provide guidance to designers, owners, and builders for improving the integration of building subsystems for energy efficiency. The lead laboratory for this program is the Pacific Northwest Laboratory. A wide variety of expertise and resources from industry, academia, other government entities, and other DOE laboratories are used in planning, reviewing and conducting research activities. Cooperative and complementary research, development, and technology transfer activities with other interested organizations are actively pursued. In this report, the interactions of a water loop heat pump system and building structural mass and their effect on whole-building energy performance is analyzed. 10 refs., 54 figs., 1 tab.
Vial, Benjamin; Hao, Yang
2015-09-01
We present the design of an all-dielectric cloaking device at microwave frequencies. A gradient based topology optimization is employed to find a dielectric permittivity distribution that minimizes the diffracted field in free space. The layout is binary, i.e. made either of standard ABS plastic or air and is designed to reduce the scattering from an ABS cylinder excited by a line source for TE polarization. We study the performances of cloaks optimized for one, two and three frequencies in terms of scattering reduction and correlations with respect to the free space propagation case. Finally, a modal analysis is carried out providing physical insights on the resonant cloaking mechanism at stake. PMID:26368452
Wave and ray analysis of a type of cloak exhibiting magnified and shifted scattering effect
Luo, Yu; Chen, Hongsheng; Wu, Bae-Ian; Ran, Lixin; Kong, Jin Au
2009-01-01
Ray-tracing exercise and full-wave analysis were performed to validate the performance of a new type of cloak composed of isotropic metamaterials. It is shown that objects inside the folded region of this cloak appear invisible to the incoming light from a ray tracing exercise, but exhibit magnified and shifted scattering under a plane wave illumination from a full wave analysis. Gaussian beams are introduced to resolve this interesting paradox resulted from these two methods. We show that at the time-harmonic state, small energy can be diffracted into the folded region and contribute to the resonant state even when the Gaussian beam is steered away from the cloak with an object inside. A scattering pattern identical to that scattered from the image of the object will be formed, which agrees well with the phenomenon in the plane wave incidence case.
Non-destructive evaluation of timber structures in a historical building of Tiradentes , MG
Luciana Barbosa de Abreu; José Tarcísio Lima; Giovanni Francisco Rabelo; Francisco Carlos Gomes; Paulo Fernando Trugilho; Felipe de Souza Eloy
2013-01-01
Problems related to the durability of wood are commonly found in historical buildings structures. Preservation and conservation resolutions must be adopted, in order to avoid losses and substitutions, which mischaracterize buildings. Non-destructive methods for detecting deterioration should be used in order to substantiate decisions and increase the longevity of historical heritage. This work was carried out in order to perform non-destructive essays to infer about the integrity of a beam an...
Analysis, Design, and Construction of a Base-Isolated Multiple Building Structure
Stefano Sorace; Gloria Terenzi
2014-01-01
The analysis and design of a multiple residential building, seismically protected by a base isolation system incorporating double friction pendulum sliders as protective devices, are presented in the paper. The building, situated in the suburban area of Florence, is composed of four independent reinforced concrete framed structures, mutually separated by three thermal expansion joints. The plan is L-shaped, with dimensions of about 75 m in the longitudinal direction and about 30 m along the l...
Directory of Open Access Journals (Sweden)
Mehmet İNEL
2007-01-01
Full Text Available Over the past several decades, Turkey has been hit by devastating earthquakes and remarkable number of reinforced concrete buildings has been damaged in the high seismicity regions of our country. The aim of this study is to evaluate the seismic performance of the mid-rise reinforced concrete buildings that are major part of building stock of our earthquake-prone country, according to recent Turkish Earthquake Code. 4- and 7-story buildings were selected to represent mid-rise building stock. After determining the structural parameters, each building was subjected to pushover analysis and the capacity curves were obtained. Earthquake performance of each building was determined in the light of their capacity curves according to the recent Turkish Earthquake Code.
International Nuclear Information System (INIS)
Three-dimensional programs were developed and proved to be fast and reliable tools for the analysis in each phase of the design of nuclear reactor building structures. Short descriptions and size of models used are given for the following analyses: preliminary analysis for all structures of a BWR reactor containment building; preliminary analysis for selection of structural solution of a reactor pedestal structure; independent checking analysis for the primary containment structures of a BWR; independent checking analysis of a reactor shield structure, and test analysis with a simplified model for the seismic response analysis of a reactor drywell structure. Description of analysis and model sizes for two complex structures is also given: building structure of a breeder reactor with detailed non-linear analysis of the internal support structure for 30 million pound hypothetic accident loads. Model sizes: 1570 and 1032 nodes respectively. Drywell structure, which serves as a primary containment and also carries the weight of the upper fuel pools. Loading conditions include internal and external pressures, thermal, seismic and other loads. Model size: 1350 nodes
Amino Acid Molecular Units: Building Primary and Secondary Protein Structures
Directory of Open Access Journals (Sweden)
Aparecido R. Silva
2008-05-01
Full Text Available In order to guarantee the learning quality and suitable knowledge use about structural biology, it is fundamental to exist, since the beginning of students’ formation, the possibility of clear visualization of biomolecule structures. Nevertheless, the didactic books can only bring schematic drawings; even more elaborated figures and graphic computation do not permit the necessary interaction. The representation of three-dimensional molecular structures with ludic models, built with representative units, have supplied to the students and teachers a successfully experience to visualize such structures and correlate them to the real molecules. The design and applicability of the representative units were discussed with researchers and teachers before mould implementation. In this stage it will be presented the developed kit containing the representative plastic parts of the main amino acids. The kit can demonstrate the interaction among the amino acids functional groups (represented by colors, shapes, sizes and the peptidic bonds between them facilitating the assembly and visuali zation of the primary and secondary protein structure. The models were designed for Ca, amino, carboxyl groups and hydrogen. The lateral chains have well defined models that represent their geometrical shape. The completed kit set will be presented in this meeting (patent requested. In the last phase of the project will be realized an effective evaluation of the kit as a facilitative didactic tool of the teaching/learning process in the Structural Molecular Biology area.
Infrared Cloaking, Stealth, and the Second Law of Thermodynamics
Directory of Open Access Journals (Sweden)
Daniel P. Sheehan
2012-10-01
Full Text Available Infrared signature management (IRSM has been a primary aeronautical concern for over 50 years. Most strategies and technologies are limited by the second law of thermodynamics. In this article, IRSM is considered in light of theoretical developments over the last 15 years that have put the absolute status of the second law into doubt and that might open the door to a new class of broadband IR stealth and cloaking techniques. Following a brief overview of IRSM and its current thermodynamic limitations, theoretical and experimental challenges to the second law are reviewed. One proposal is treated in detail: a high power density, solid-state power source to convert thermal energy into electrical or chemical energy. Next, second-law based infrared signature management (SL-IRSM strategies are considered for two representative military scenarios: an underground installation and a SL-based jet engine. It is found that SL-IRSM could be technologically disruptive across the full spectrum of IRSM modalities, including camouflage, surveillance, night vision, target acquisition, tracking, and homing.
Building chessboard-like supramolecular structures on Au(111) surfaces
Dou, Ruifen; Yang, Yu; Zhang, Ping; Zhong, Dingyong; Fuchs, Harald; Wang, Yue; Chi, Lifeng
2015-09-01
We investigate an anthracene derivative, 3(5)-(9-anthryl) pyrazole (ANP), self-assembled on the Au(111) surface by means of scanning tunneling microscopy (STM) and density functional theory (DFT) calculations. A chessboard-like network structure composed of ANP molecules is found, covering the whole Au(111) substrate. Our STM results and DFT calculations reveal that the formation of chessboard-like networks originates from a basic unit cell, a tetramer structure, which is formed by four ANP molecules connected through C-H…N hydrogen bonds. The hydrogen bonds inside each tetramer and the molecule-substrate interaction are fundamentally important in providing a driving force for formation of the supramolecular networks.
Principles of structure building in music, language and animal song
Rohrmeier, Martin; Zuidema, Willem; Wiggins, Geraint A.; Scharff, Constance
2015-01-01
Human language, music and a variety of animal vocalizations constitute ways of sonic communication that exhibit remarkable structural complexity. While the complexities of language and possible parallels in animal communication have been discussed intensively, reflections on the complexity of music and animal song, and their comparisons, are underrepresented. In some ways, music and animal songs are more comparable to each other than to language as propositional semantics cannot be used as in...
Data Structure Estimation for RDF Oriented Repository Building
Czech Academy of Sciences Publication Activity Database
Řimnáč, Martin
Los Alamitos : IEEE Computer Society, 2007 - (Barolli, L.; Tjoa, A.), s. 147-154 ISBN 0-7695-2823-6. [CISIS'07. International Conference on Complex, Intelligent and Software Intensive Systems /1./. Vienna (AT), 10.04.2007-13.04.2007] R&D Projects: GA AV ČR 1ET100300419 Institutional research plan: CEZ:AV0Z10300504 Keywords : data structure estimation * functional dependency discovery * semantic web Subject RIV: IN - Informatics, Computer Science
Application of modern control theory for building structures
Basharkhah, M. A.; Yao, J. T. P.
The design of feedback compensators is considered for linear and constant-coefficient multivariable systems and an attempt is made to find a suitable gain matrix for active control of structures. The application of the pole-assignment method is discussed. It is based on the shifting of open-loop poles to the left side of the s-plane, and is applicable to mechanical and electrical systems. The second method developed in this study provides a physical understanding of the active control of civil engineering structures because it allows control of several modes of the system. The K matrix of the control law can be found so that the first few modes of the system have smaller displacements than the corresponding displacements of the original system. Therefore, more modes of higher gain can be used to substantially reduce system displacements. Because the pole-assignment method will not always significantly reduce displacements, the second method is found to be better for the control of civil engineering structures.
International Nuclear Information System (INIS)
During the period of October 15 and 18, 2007, ORISE performed confirmatory radiological survey activities which included beta and gamma structural surface scans and beta activity direct measurements within the Auxiliary Building, beta or gamma scans within Turbine Building embedded piping, beta activity determinations within Turbine Building Drain 3-1-27, and gamma scans and the collection of a soil sample from the clay soils adjacent to the Lower Mixing Box
International Nuclear Information System (INIS)
During the period of October 15 and 18, 2007, ORISE performed confirmatory radiological survey activities which included beta and gamma structural surface scans and beta activity direct measurements within the Auxiliary Building, beta or gamma scans within Turbine Building embedded piping, beta activity determinations within Turbine Building Drain 3-1-27, and gamma scans and the collection of a soil sample from the clay soils adjacent to the Lower Mixing Box
International Nuclear Information System (INIS)
This work aims at improving and validating methods coupling Finite Element (FE) and Boundary Element (BE) Methods in the context of Soil-Structure Interaction (SSI) and Structure-Soil-Structure Interaction (3SI) tests performed by NUPEC on mock-up structures built on an unmade ground. Several cases have been tested: single and juxtaposed buildings, shallow and embedded foundations, with various loading conditions: forced and natural seismic loadings. The numerical simulations of forced vibration tests are in good agreement with the results of the NUPEC experiments in the case of two embedded buildings either in terms of amplitude and resonance. The numerical simulation of seismic response tests by FEM and BEM allows for a proper choice of the 'reference point' where the computed and the experimental displacements coincide. A parametric analysis of Structure-Soil-Structure Interaction carried out by the FEM has allowed to determine the influence of some parameters on SSI. Most of them like the position of the building in the excavation, the direction of the load, the quality of the contact between the sidewalls of the buildings and the soil for embedded foundations, do not show to have a strong influence on the dynamic system behaviour, which is mainly governed by the stiffness of the first soil layer. As far as 3SI is concerned, this paper shows that when the cross interaction has a small effect on the building response in the case of surface foundations, it has a strong influence in the case of embedded foundations with an important decrease of the response at the top of the buildings. (authors)
Building a Data Store with the Dynamic Structure
Directory of Open Access Journals (Sweden)
Yu. N. Artamonov
2016-01-01
Full Text Available This article presents the analysis of approaches to data warehouse construction based on relational and NoSQL solutions and lists the limitations of the relational approach to data mining. The contradiction between data presentation in the real subject domain and the model of data presentation in the relational and NoSQL approaches is revealed. The revealed contradiction is related to the temporality of the values of individual data attributes, the variability of the composition of these attributes, and structure of connections between them. A new logical model of the data warehouse with dynamic structure is proposed. The model is based on the concept of the object as a container for properties storage. Each property of the object includes the property name and two property values without reference and with reference, that are relevant at a given time. The reference property value points to an object whose name is interpreted as the value of the property at a given time. A formal description of the model with allocation of the necessary functionality to manipulate objects and their properties (selectors, predicates, constructors is given and the necessary control structures are introduced. Substantiation of the proposed model, called an OP-model is given on the basis of compliance with the logical ER data model. It is proved that any ER data model can be implemented in the OP-model. At the same time, the advantages of the OP-model are indicated, they are associated with the possibility of changing connections between entities due to changes in the reference value at a particular time. The potential for scalability of data warehouse due to the unique identification of each object is noted.
Extraordinary surface voltage effect in the invisibility cloak with an active device inside
Zhang, Baile; Wu, Bae-Ian; Kong, Jin Au
2007-01-01
The electromagnetic field solution for a spherical invisibility cloak with an active device inside is established. It is found that extraordinary electric and magnetic surface voltages are induced at the inner boundary of a spherical cloak, which prevent electromagnetic waves from going out. The phase and handness information of polarized waves obliquely incident on such special boundaries is kept in the reflected waves. The values of the surface voltages due to an electric dipole with an arbitrary position inside the concealed region are found to be equal to the auxiliary scalar potentials, which consequently gain physical counterparts in this special case.
Design of two-dimensional elliptically cylindrical invisible cloaks with multiple regions
International Nuclear Information System (INIS)
Two-dimensional (2D) elliptically cylindrical invisible cloaks with multiple regions are designed based on the transformation optics and the complementary media theory. Multiple invisible cloak regions can be obtained by properly using the compressed or folded transformation in each space layer. The constitutive parameter tensor expressions for each region have been obtained. The results of full wave simulations by using finite element software confirm the validity of the constitutive parameter tensor expressions. In addition, the parameters are relatively easier to realize. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)
Time gap for temporal cloak based on spectral hole burning in atomic medium
Jabar, M. S. Abdul; Bacha, Bakht Amin; Ahmad, Iftikhar
2016-08-01
We demonstrate the possibility of creating a time gap in the slow light based on spectral hole burning in a four-level Doppler broadened sodium atomic system. A time gap is also observed between the slow and the fast light in the hole burning region and near the burnt hole region, respectively. A cloaking time gap is attained in microseconds and no distortion is observed in the transmitted pulse. The width of the time gap is observed to vary with the inverse Doppler effect in this system. Our results may provide a way to create multiple time gaps for a temporal cloak. Project supported by the Higher Education Commission (HEC) of Pakistan.
Building the meaning of preference from logical paired structures
DEFF Research Database (Denmark)
Franco, Camilo; Rodríguez, J. Tinguaro; Montero, Javier
2015-01-01
Making decisions by learning preferences requires to consider semantical aspects dealing with the meaning and use of the preference concept. Examining recent developments on bipolarity, where concepts are measured/verified regarding a pair of opposite poles, we focus on the dialectic process by...... which the meaning of concepts emerges. Our proposal is based on the neutrality in between the opposite poles, such that a basic type of structure is used to characterize in logical terms the concepts and the knowledge that they generate. In this paper we model the meaning of concepts by paired...
Stellar structure and the art of building boats
Celnikier, Ludwik M.
1989-02-01
Acton and Squire's [Solving Equations with Physical Understanding (Hilger, Bristol, 1985)] ``trial function'' method of handling boundary value problems is used to find approximate solutions to the equations of stellar structure; the calculations involved are as simple to carry out as the usual order-of-magnitude estimates, but are correct to a few tens of a percent. The method is also used to investigate why an order-of-magnitude estimate of solar luminosity can be wrong by up to three orders of magnitude, while a similar estimate of the central temperature can be closer to acceptable values.
Towards composite spheres as building blocks for structured molecules.
Lee, Lloyd L; Pellicane, Giuseppe
2016-10-19
In order to design a flexible molecular model that mimics the chemical moieties of a polyatomic molecule, we propose the 'composite-sphere' model that can assemble the essential elements to produce the structure of the target molecule. This is likened to the polymerization process where monomers assemble to form the polymer. The assemblage is built into the pair interaction potentials which can 'react' (figuratively) with selective pieces into various bonds. In addition, we preserve the spherical symmetries of the individual pair potentials so that the isotropic Ornstein-Zernike equation (OZ) for multi-component mixtures can be used as a theoretical framework. We first test our approach on generating a dumbbell molecule. An equimolar binary mixture of hard spheres and square-well spheres are allowed to react to form a dimer. As the bond length shrinks to zero, we create a site-site model of a Janus-like molecule with a repulsive moiety and an attractive moiety. We employ the zero-separation (ZSEP) closure to solve the OZ equations. The structure and thermodynamic properties are calculated at three isotherms and at several densities and the results are compared with Monte Carlo simulations. The close agreement achieved demonstrates that the ZSEP closure is a reliable theory for this composite-sphere fluid model. PMID:27546819
International Nuclear Information System (INIS)
Recent terrorist attacks using commandeered commercial airliners on civil structures have raised the issue of the ability of nuclear power plants to survive the consequences of an airliner crash. The structural integrity analysis due to the effects of an aircraft crash on an Ignalina nuclear power plant (INPP) accident localization system (ALS) building is the subject of this paper. A combination of the finite element method and empirical relationships were used for the analysis. A global structural integrity analysis was performed for a portion of the ALS building using the dynamic loading from an aircraft crash impact model. The local effects caused by impact of the aircraft's engine on the building wall were evaluated independently by using an empirical formula. The results from the crash analysis of a twin engine commercial aircraft show that the impacted reinforced concrete wall of the ALS building will not have through-the-wall concrete failure, and the reinforcement will not fail. Strain-rate effects were found to delay the onset of cracking. Therefore, the structural integrity of the impacted wall of the INPP ALS building will be maintained during the crash event studied
Incorporating Soil-Structure Interaction intoSeismic Response Analyses for Buildings
Stewart, Jonathan P.; Mylonakis, George; Givens, Michael J; Crouse, CB; Hutchinson, Tara; Lizundia, Bret; Naeim, Farzad; Ostadan, Farhang; Heintz, Jon A
2014-01-01
Soil-structure interaction (SSI) analysis evaluates the collective response anddynamic interplay of three linked systems: the structure, the foundation, and the soil underlying and surrounding the foundation. Problems associated with practical application of SSI for building structures are rooted in a poor understanding of fundamental SSI principles. Implementation in practice is hindered by a literature that is difficult to understand, and codes and standards that contain limited guidance an...
Building Classroom and Organizational Structure Around Positive Cultural Values
Albanna, Badr F; Dounas-Frazer, Dimitri R; Little, Angela; Zaniewski, Anna M
2012-01-01
The Compass Project is a self-formed group of graduate and undergraduate students in the physical sciences at UC Berkeley. Our goals are to improve undergraduate physics education, provide opportunities for professional development, and increase retention of students-especially those from populations typically underrepresented in the physical sciences. Compass fosters a diverse, collaborative student community by providing a wide range of services, including a summer program and fall/spring seminar courses. We describe Compass's cultural values, discuss how community members are introduced to and help shape those values, and demonstrate how a single set of values informs the structure of both our classroom and organization.We emphasize that all members of the Compass community participate in, and benefit from, our cultural values, regardless of status as student, teacher, or otherwise.
Soil structure interaction analysis for a reactor building with a pile foundation system
International Nuclear Information System (INIS)
The present paper presents the SSI analysis and Floor Response Spectra (FRS) generation for a Reactor Building (RB) with a pile foundation system. This work was done within the scope of Probabilistic Safety Analysis Level 1 - external events, (1993). The task was to produce the best estimated seismic structure response including FRS and seismic displacements, taking into account the SSI effects. The uniform hazard ground response spectra, was provided by seismological studies. The soil dynamic parameters are based on site measurements. The analysis was carried out using two parallel methods in order to calibrate the analytical models and to create cross check. The analysis flow chart is presented. In addition analyses of building - soil -building interaction and equipment - building interaction were performed to determine the best estimated relative displacements between the supports points of the main steam line. (author). 8 refs., 5 figs., 5 tabs
Directory of Open Access Journals (Sweden)
Sangyong Kim
2014-03-01
Full Text Available This study aims to present an efficient plan for the application of a geothermal energy facility at the building structure planning phase. Energy consumption, energy cost and the primary energy consumption of buildings were calculated to enable a comparison of buildings prior to the application of a geothermal energy facility. The capacity for energy savings and the costs related to the installation of such a facility were estimated. To obtain more reliable criteria for economic feasibility, the lifecycle cost (LCC analysis incorporated maintenance costs (reflecting repair and replacement cycles based on construction work specifications of a new renewable energy facility and initial construction costs (calculated based on design drawings for its practical installation. It is expected that the findings of this study will help in the selection of an economically viable geothermal energy facility at the building construction planning phase.
Soil structure interaction analysis for a reactor building with a pile foundation system
Energy Technology Data Exchange (ETDEWEB)
Coman, O. [Stevenson and Associates Office in Bucharest, (Romania); Ree, H. van de [N.V. Kema, Arnhem (Netherlands). Transmission and Distribution
1995-12-31
The present paper presents the SSI analysis and Floor Response Spectra (FRS) generation for a Reactor Building (RB) with a pile foundation system. This work was done within the scope of Probabilistic Safety Analysis Level 1 - external events, (1993). The task was to produce the best estimated seismic structure response including FRS and seismic displacements, taking into account the SSI effects. The uniform hazard ground response spectra, was provided by seismological studies. The soil dynamic parameters are based on site measurements. The analysis was carried out using two parallel methods in order to calibrate the analytical models and to create cross check. The analysis flow chart is presented. In addition analyses of building - soil -building interaction and equipment - building interaction were performed to determine the best estimated relative displacements between the supports points of the main steam line. (author). 8 refs., 5 figs., 5 tabs.
Seismic response of tall building considering soil-pile-structure interaction
Han, Yingcai
2002-06-01
The seismic behavior of tall buildings can be greatly affected by non-linear soil-pile interaction during strong earthquakes. In this study a 20-storey building is examined as a typical structure supported on a pile foundation for different conditions: (1) rigid base, i.e. no deformation in the foundation: (2) linear soil-pile system; and (3) nonlinear soil-pile system. The effects of pile foundation displacements on the behavior of tall building are investigated, and compared with the behavior of buildings supported on shallow foundation. With a model of non-reflective boundary between the near field and far field, Novak’s method of soil-pile interaction is improved. The computation method for vibration of pile foundations and DYNAN computer program are introduced comprehensively. A series of dynamic experiments have been done on full-scale piles, including single pile and group, linear vibration and nonlinear vibration, to verify the validity of boundary zone model.
Behaviour of AR glass fibre for building structural applications
Directory of Open Access Journals (Sweden)
Miravete, A.
2005-12-01
Full Text Available The AR glass reinforcement fibres were designed to resist the alkalis from the concrete. This is the main reason for its utilisation as a short-fibre-reinforcement of mortar and concrete for the last decades. Originally, the AR glass fibre sizing was not compatible with synthetic resins, so that this type of reinforcement was applied exclusively to mortar and concrete matrices. Recently, due to the developments of sizing, which are compatible with synthetic resins, the AR- glass fibres may be used as reinforcement of organic matrix composite materials, broadening the range of structural applications. The mechanical properties of AR glass fibre and organic matrix composite materials will be studied in this paper. First, the behaviour of this material under stress corrosion will be analysed. Their mass loss will be compared to E, C, and boron free glass fibres. Second, an experimental study dealing with 3P test bending and short beam ofAR glass fibre/polyester will de described with the goal of obtaining their Young modulus and tensile and interlaminar shear strengths. Finally, these experimental results will be compared to E glass fibre/polyester and several conclusions about their structural applications will be drawn.
El vidrio AR y su presentación en forma de fibras de refuerzo, fue diseñado para ser inerte a los álcalis de los cementos. Por este motivo se viene utilizando desde hace varias décadas como refuerzo de morteros y hormigones en forma de fibra corta. El ensimaje que estas fibras de vidrio de refuerzo A R presentaba en su origen no era compatible con resinas de tipo sintéticas, por lo que el refuerzo era exclusivo para cementos y hormigones fuera cual fuera la aplicación, formato o proceso productivo. Recientemente, gracias al desarrollo específico de ensimajes especiales acordes a las fibras de vidrio AR ha aparecido la misma tipología de vidrio AR como refuerzo en forma de fibra continua compatible con resinas sint
Max Auwaerter Price lecture: building and probing atomic structures
International Nuclear Information System (INIS)
Full text: The control of the geometric, electronic, and magnetic properties of atomic-scale nanostructures is a prerequisite for the understanding and fabrication of new materials and devices. Two routes lead towards this goal: Atomic manipulation of single atoms and molecules by scanning probe microscopy, or patterning using self-assembly. Atomic manipulation has been performed since almost 20 years, but it has been difficult to answer the simple question: how much force does it take to manipulate atoms and molecules on surfaces? To address this question, we used a combined atomic force and scanning tunneling microscope to simultaneously measure the force and the current between an adsorbate and a tip during atomic manipulation. We found that the force it takes to move an atom depends crucially on the binding between adsorbate and surface. Our results indicate that for moving metal atoms on metal surfaces, the lateral force component plays the dominant role. Measuring the forces during manipulation yielded the full potential energy landscape of the tip-sample interaction. Surprisingly, the potential energy barriers are comparable to diffusion barriers, which are obtained in the absence of a probe tip. Furthermore, we used the scanning tunneling microscope to assemble magnetic structures on a thin insulator. We found, that the spin of the atom is influenced by the magnetocrystalline anisotropy of the supporting surface which lifts the spin degeneracy of the ground state and enables the identification of individual atoms. The ground state of atoms with half-integer spin remains always degenerated at zero field due to Kramers theorem. We found that if these states differ by an orbital momentum of m = ±1 the localized spin is screened by the surrounding conducting electrons of the non-magnetic host and form a many-electron spin-singlet at sufficiently low temperature. (author)
Task 7a: Dynamic analysis of Paks NPP structures reactor building
International Nuclear Information System (INIS)
This report describes dynamic response calculation of the NPP Paks, reactor building to the full scale blast testing. All calculations described in this report have been elaborated within the scope of IAEA co-ordinated research - Benchmark Study for for seismic analysis/testing of NPPs type WWER - Task 7a - Dynamic Analysis of PAKS NPP structures, i.e. reactor building. The input in the form of time history of velocities or accelerations on the free field caused by blast testing was only available for the participants of the task No.7a. The aim of this task is to calculate the dynamic response to the blast load in the form of floor response spectra in selected nodes of the structure without knowing the measured data. The data measured by the full scale blast test are published and the results of different calculations compared. The following structures were taken into account: turbine hall, intermediate multi-storey building, lateral multi-storey building, reactor building, ventilation center and condenser towers
Automatic building of a web-like structure based on thermoplastic adhesive
International Nuclear Information System (INIS)
Animals build structures to extend their control over certain aspects of the environment; e.g., orb-weaver spiders build webs to capture prey, etc. Inspired by this behaviour of animals, we attempt to develop robotics technology that allows a robot to automatically builds structures to help it accomplish certain tasks. In this paper we show automatic building of a web-like structure with a robot arm based on thermoplastic adhesive (TPA) material. The material properties of TPA, such as elasticity, adhesiveness, and low melting temperature, make it possible for a robot to form threads across an open space by an extrusion-drawing process and then combine several of these threads into a web-like structure. The problems addressed here are discovering which parameters determine the thickness of a thread and determining how web-like structures may be used for certain tasks. We first present a model for the extrusion and the drawing of TPA threads which also includes the temperature-dependent material properties. The model verification result shows that the increasing relative surface area of the TPA thread as it is drawn thinner increases the heat loss of the thread, and that by controlling how quickly the thread is drawn, a range of diameters can be achieved from 0.2–0.75 mm. We then present a method based on a generalized nonlinear finite element truss model. The model was validated and could predict the deformation of various web-like structures when payloads are added. At the end, we demonstrate automatic building of a web-like structure for payload bearing. (paper)
Building Structural Complexity in Semiconductor Nanocrystals through Chemical Transformations
Energy Technology Data Exchange (ETDEWEB)
Sadtler, Bryce F [Univ. of California, Berkeley, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
2009-05-01
Ag_{2}S lattices were used to calculate interface formation energies. The formation energies indicate the favorability for interface nucleation at different facets of the nanorod and the stability of the interfaces during growth of the secondary material (Cu_{2}S or Ag_{2}S) within the CdS nanocrystal. The physical properties of the CdS-Ag_{2}S and CdS-Cu2S binary nanorods are discussed in terms of the electronic structure of their components and the heterostructure morphology.
Schofield, R. S.; Soric, J. C.; Rainwater, D.; Kerkhoff, A.; Alù, A.
2014-06-01
A simple, thin, flexible mantle cloak for conducting rods based on scattering cancellation is analyzed, designed and experimentally realized. We show strong scattering suppression at all angles of incidence, for both far-field plane-wave and near-field Gaussian excitations. The required effective shunt surface impedance is realized by a subwavelength patch array, targeting the suppression of the dominant omnidirectional scattering contribution of a conductive rod. Full-wave simulations predict a total radar cross-section reduction better than 14 dB in the lossless case and nearly 8 dB when considering a lossy substrate in the cover. Measurements of the realized cloak are consistent and validate these numerical predictions. The proposed geometry is also shown to be an ideal platform for monolithic integration of varactor diodes, allowing real-time tuning of the effective surface capacitance of the cloak. We show with numerical simulations the possibility of tunable scattering suppression over 1 GHz of bandwidth by seamlessly integrating varactor diodes in our mantle cloak design.
Electromagnetic cloak to restore the antenna radiation patterns affected by nearby scatter
Energy Technology Data Exchange (ETDEWEB)
Teperik, Tatiana V., E-mail: tatiana.teperik@u-psud.fr [Univ. Paris-Sud, Institut d’Electronique Fondamentale, UMR 8622, Orsay F-91405 (France); Donostia International Physics Center, Aptdo. 1072, 20080 San Sebastian (Spain); Lustrac, André de [Univ. Paris-Sud, Institut d’Electronique Fondamentale, UMR 8622, Orsay F-91405 (France); Univ. Paris-Ouest, 92410 Ville d’Avray (France)
2015-12-15
We have theoretically verified the feasibility of the concept of mantle cloak for very high frequency (VHF) antenna communications. While the applicability of the concept has been demonstrated for an infinitely long cylindrical obstacle and infinitely long electric source [Y.R. Padooru, A.B. Yakovlev, and P.-Y. Chen and Andrea Alù, J. Appl. Phys., 112, 104902, (2012)], the use of this cloak in realistic conditions is not straightforward. In this paper as an electric source we consider a typical VHF monopole antenna mounted on ground plane together with a metallic cylindrical obstacle. The both ground plane and obstacle affect the antenna radiation scattering. Nevertheless, we could show that the mantle cloak can bee successfully applied to restore the radiation patterns of antenna even when the source, the cylindrical metallic obstacle, and the ground plane have finite length. We have studied the antenna adaptation in the presence of the cloaked obstacle and found that the complete radiation system is still functional in the bandwidth that is reduced only by 11%.
International Nuclear Information System (INIS)
A simple, thin, flexible mantle cloak for conducting rods based on scattering cancellation is analyzed, designed and experimentally realized. We show strong scattering suppression at all angles of incidence, for both far-field plane-wave and near-field Gaussian excitations. The required effective shunt surface impedance is realized by a subwavelength patch array, targeting the suppression of the dominant omnidirectional scattering contribution of a conductive rod. Full-wave simulations predict a total radar cross-section reduction better than 14 dB in the lossless case and nearly 8 dB when considering a lossy substrate in the cover. Measurements of the realized cloak are consistent and validate these numerical predictions. The proposed geometry is also shown to be an ideal platform for monolithic integration of varactor diodes, allowing real-time tuning of the effective surface capacitance of the cloak. We show with numerical simulations the possibility of tunable scattering suppression over 1 GHz of bandwidth by seamlessly integrating varactor diodes in our mantle cloak design. (paper)
Beam Steering at Higher Photonic Bands and Design of a Directional Cloak Formed by Photonic Crystals
Directory of Open Access Journals (Sweden)
Venkatachalam Subramanian
2013-02-01
Full Text Available Beam steering due to anomalous dispersion at higher photonic bands in dielectric photonic crystal is reported in this work. Based on this concept, directional cloak is designed that conceals a larger dimensional scattering object against the normal incident, linearly polarizedelectromagnetic waves.
Beam Steering at Higher Photonic Bands and Design of a Directional Cloak Formed by Photonic Crystals
Venkatachalam Subramanian; Natesan Yogesh
2013-01-01
Beam steering due to anomalous dispersion at higher photonic bands in dielectric photonic crystal is reported in this work. Based on this concept, directional cloak is designed that conceals a larger dimensional scattering object against the normal incident, linearly polarizedelectromagnetic waves.
Electromagnetic cloak to restore the antenna radiation patterns affected by nearby scatter
International Nuclear Information System (INIS)
We have theoretically verified the feasibility of the concept of mantle cloak for very high frequency (VHF) antenna communications. While the applicability of the concept has been demonstrated for an infinitely long cylindrical obstacle and infinitely long electric source [Y.R. Padooru, A.B. Yakovlev, and P.-Y. Chen and Andrea Alù, J. Appl. Phys., 112, 104902, (2012)], the use of this cloak in realistic conditions is not straightforward. In this paper as an electric source we consider a typical VHF monopole antenna mounted on ground plane together with a metallic cylindrical obstacle. The both ground plane and obstacle affect the antenna radiation scattering. Nevertheless, we could show that the mantle cloak can bee successfully applied to restore the radiation patterns of antenna even when the source, the cylindrical metallic obstacle, and the ground plane have finite length. We have studied the antenna adaptation in the presence of the cloaked obstacle and found that the complete radiation system is still functional in the bandwidth that is reduced only by 11%
Electromagnetic cloak to restore the antenna radiation patterns affected by nearby scatter
Directory of Open Access Journals (Sweden)
Tatiana V. Teperik
2015-12-01
Full Text Available We have theoretically verified the feasibility of the concept of mantle cloak for very high frequency (VHF antenna communications. While the applicability of the concept has been demonstrated for an infinitely long cylindrical obstacle and infinitely long electric source [Y.R. Padooru, A.B. Yakovlev, and P.-Y. Chen and Andrea Alù, J. Appl. Phys., 112, 104902, (2012], the use of this cloak in realistic conditions is not straightforward. In this paper as an electric source we consider a typical VHF monopole antenna mounted on ground plane together with a metallic cylindrical obstacle. The both ground plane and obstacle affect the antenna radiation scattering. Nevertheless, we could show that the mantle cloak can bee successfully applied to restore the radiation patterns of antenna even when the source, the cylindrical metallic obstacle, and the ground plane have finite length. We have studied the antenna adaptation in the presence of the cloaked obstacle and found that the complete radiation system is still functional in the bandwidth that is reduced only by 11%.
Electromagnetic cloak to restore the antenna radiation patterns affected by nearby scatter
Teperik, Tatiana V.; de Lustrac, André
2015-12-01
We have theoretically verified the feasibility of the concept of mantle cloak for very high frequency (VHF) antenna communications. While the applicability of the concept has been demonstrated for an infinitely long cylindrical obstacle and infinitely long electric source [Y.R. Padooru, A.B. Yakovlev, and P.-Y. Chen and Andrea Alù, J. Appl. Phys., 112, 104902, (2012)], the use of this cloak in realistic conditions is not straightforward. In this paper as an electric source we consider a typical VHF monopole antenna mounted on ground plane together with a metallic cylindrical obstacle. The both ground plane and obstacle affect the antenna radiation scattering. Nevertheless, we could show that the mantle cloak can bee successfully applied to restore the radiation patterns of antenna even when the source, the cylindrical metallic obstacle, and the ground plane have finite length. We have studied the antenna adaptation in the presence of the cloaked obstacle and found that the complete radiation system is still functional in the bandwidth that is reduced only by 11%.
Influence of Structural Periodicity on Vibration Transmission in a Multi-Storey Wooden Building
DEFF Research Database (Denmark)
Andersen, Lars Vabbersgaard
2013-01-01
Noise is a nuisance to people, and buildings should therefore be designed to prevent propagation of sound and vibration in the audible frequency range as well as the range of frequencies relevant to whole-body vibrations of humans. In heavy structures made of concrete and masonry, a source with h...
49 CFR 1242.26 - Miscellaneous building and structures (account XX-19-28).
2010-10-01
... 49 Transportation 9 2010-10-01 2010-10-01 false Miscellaneous building and structures (account XX... XX-19-28). Separate common expenses as specific facts indicate or according to distribution of common expenses listed in § 1242.10, Administration-Track (account XX-19-02)....
The integration of water loop heat pump and building structural thermal storage systems
Energy Technology Data Exchange (ETDEWEB)
Marseille, T.J.; Schliesing, J.S.
1990-09-01
Commercial buildings often have extensive periods where one space needs cooling and another heating. Even more common is the need for heating during one part of the day and cooling during another in the same spaces. If a building's heating and cooling system could be integrated with the building's structural mass such that the mass can be used to collect, store, and deliver energy, significant energy might be saved. Computer models were developed to simulate this interaction for an existing office building in Seattle, Washington that has a decentralized water-source heat pump system. Metered data available for the building was used to calibrate a base'' building model (i.e., nonintegrated) prior to simulation of the integrated system. In the simulated integration strategy a secondary water loop was manifolded to the main HVAC hydronic loop. tubing in this loop was embedded in the building's concrete floor slabs. Water was routed to this loop by a controller to charge or discharge thermal energy to and from the slabs. The slabs were also in thermal communication with the conditioned spaces. Parametric studies of the building model, using weather data for five other cities in addition to Seattle, predicted that energy can be saved on cooling dominated days. On hot, dry days and during the night the cooling tower can beneficially be used as a free cooling'' source for thermally charging'' the floor slabs using cooled water. Through the development of an adaptive/predictive control strategy, annual HVAC energy savings as large as 30% appear to be possible in certain climates. 8 refs., 13 figs.
Kosny, Jan
2015-01-01
Presenting an overview of the use of Phase Change Materials (PCMs) within buildings, this book discusses the performance of PCM-enhanced building envelopes. It reviews the most common PCMs suitable for building applications, and discusses PCM encapsulation and packaging methods. In addition to this, it examines a range of PCM-enhanced building products in the process of development as well as examples of whole-building-scale field demonstrations. Further chapters discuss experimental and theoretical analyses (including available software) to determine dynamic thermal and energy performance ch
On the use of tensegrity structures for kinetic solar facades of smart buildings
Fraternali, F.; De Chiara, E.; Skelton, R. E.
2015-10-01
We investigate the use of tensegrity structures with morphing and prestress-stability capabilities for the design of active solar façades of smart buildings. Morphing tensegrity lattices are used to design shading screens composed of umbrella-shaped ‘eyes’ that are opened and closed by adjusting the elongation in a limited number of cables. Prestressable lattices are instead employed to design superstable Venetian blinds that are composed of orientable slats. Future use of tensegrity solutions for next-generation smart buildings are outlined, with the aim of designing kinetic solar façades that combine morphing abilities with prestress-stability.
Influence of Building Material Solution of Structures to Effectiveness of Real Estate Development
Somorová, Viera
2015-11-01
Real estate development is in its essence the development process characterized by a considerable dynamics. The purpose of the development process is the creation of buildings which can be either rented by future unknown users or sold in the real estate market. A first part of the paper is dedicated to the analysis of the parameters of buildings solutions considering the future operating costs in a phase of designing. Material solution of external structures is a main factor not only in determining the future operating costs but also in achieving the subsequent economic effectiveness of the real estate development. To determine the relationship between economic efficiency criteria and determine the optimal material variant of building constructions for the specific example is the aim of the second part of paper.
Seismic response of tall building considering soil-pile-structure interaction
Institute of Scientific and Technical Information of China (English)
无
2002-01-01
The seismic behavior of tall buildings can be greatly affected by non-linear soil-pile interaction during strongearthquakes. In this study a 20-storey building is examined as a typical structure supported on a pile foundation for differentconditions: (1) rigid base, i.e. no deformation in the foundation: (2) linear soil-pile system; and (3) nonlinear soil-pile system.The effects of pile foundation displacements on the behavior of tall building are investigated, and compared with the behavior ofbuildings supported on shallow foundation. With a model of non-reflective boundary between the near field and far field,Novak's method of soil-pile interaction is improved. The computation method for vibration of pile foundations and DYNANcomputer program are introduced comprehensively. A series of dynamic experiments have been done on full-scale piles,including single pile and group, linear vibration and nonlinear vibration, to verify the validity of boundary zone model.
Directory of Open Access Journals (Sweden)
Sangyong Kim
2013-01-01
Full Text Available The objective of this research is to quantitatively measure and compare the environmental load and construction cost of different structural frame types. Construction cost also accounts for the costs of CO2 emissions of input materials. The choice of structural frame type is a major consideration in construction, as this element represents about 33% of total building construction costs. In this research, four constructed buildings were analyzed, with these having either reinforced concrete (RC or steel (S structures. An input-output framework analysis was used to measure energy consumption and CO2 emissions of input materials for each structural frame type. In addition, the CO2 emissions cost was measured using the trading price of CO2 emissions on the International Commodity Exchange. This research revealed that both energy consumption and CO2 emissions were, on average, 26% lower with the RC structure than with the S structure, and the construction costs (including the CO2 emissions cost of the RC structure were about 9.8% lower, compared to the S structure. This research provides insights through which the construction industry will be able to respond to the carbon market, which is expected to continue to grow in the future.
Kim, Sangyong; Moon, Joon-Ho; Shin, Yoonseok; Kim, Gwang-Hee; Seo, Deok-Seok
2013-01-01
The objective of this research is to quantitatively measure and compare the environmental load and construction cost of different structural frame types. Construction cost also accounts for the costs of CO₂ emissions of input materials. The choice of structural frame type is a major consideration in construction, as this element represents about 33% of total building construction costs. In this research, four constructed buildings were analyzed, with these having either reinforced concrete (RC) or steel (S) structures. An input-output framework analysis was used to measure energy consumption and CO₂ emissions of input materials for each structural frame type. In addition, the CO₂ emissions cost was measured using the trading price of CO₂ emissions on the International Commodity Exchange. This research revealed that both energy consumption and CO₂ emissions were, on average, 26% lower with the RC structure than with the S structure, and the construction costs (including the CO₂ emissions cost) of the RC structure were about 9.8% lower, compared to the S structure. This research provides insights through which the construction industry will be able to respond to the carbon market, which is expected to continue to grow in the future. PMID:24227998
Coupling of impedance functions to nuclear reactor building for soil-structure interaction analysis
International Nuclear Information System (INIS)
Finite element model of a nuclear reactor building is coupled to complex soil impedance functions and soil-structure-interaction analysis is carried out in frequency domain. In the second type of analysis applied in this paper, soil impedance functions are used to evaluate equivalent soil springs and dashpots of soil. These are coupled to the structure model in order to carry out the time marching analysis. Three types of soil profiles are considered: hard, medium and soft. Results of two analyzes are compared on the same structural model. Equivalent soil springs and dashpots are determined using new method based on the least square approximation. (author)
Krzyżek, Robert
2015-12-01
The paper deals with the problem of surveying buildings in the RTN GNSS mode using modernized indirect methods of measurement. As a result of the classical realtime measurements using indirect methods (intersection of straight lines or a point on a straight line), we obtain a building structure (a building) which is largely deformed. This distortion is due to the inconsistency of the actual dimensions of the building (tie distances) relative to the obtained measurement results. In order to eliminate these discrepancies, and thus to ensure full consistency of the building geometric structure, an innovative solution was applied - the method of vector addition - to modify the linear values (tie distances) of the external face of the building walls. A separate research problem tackled in the article, although not yet fully solved, is the issue of coordinates of corners of a building obtained after the application of the method of vector addition.
Design of earthquake resistance enhancements of the Dukovany nuclear power plant building structures
International Nuclear Information System (INIS)
The paper deals with problems of enhancing earthquake resistance of safety related building structures of the NPP Dukovany. The plant operates for over thirty years and there is time to verify the actual state of structures. Two years ago a detailed seismic response analysis of structures considering the newly postulated earthquake loads has been performed. The computation model has been developed involving the complex of all interacting structures of the main production block with equipment. Seismic analysis has been performed using response spectrum method. The reliability assessment of structures has been carried out. Consequently feasible ways of enhancing the seismic resistance of structures have been designed. In order to verify the designs a second seismic analysis has been recently accomplished using acceleration time history method. The results of analyses are discussed in the paper. (author)
Seismic safety evaluation of base-isolated building structures in Japan
Energy Technology Data Exchange (ETDEWEB)
Kitagawa, Yoshikazu; Midorikawa, Mitsumasa [Ministry of Construction, Tsukuba, Ibaraki (Japan)
1995-12-01
Japan is characteristically subjected to seismic activity. Therefore, it is a matter of concern how building structures behave under earthquake conditions. Currently, the focus of research on seismic design methods has changed from static analysis to dynamic one. Many studies and proposals concerned with base-isolation systems have been carried out, some of which have resulted in the construction of actual structures in New Zealand, France, U.S.A., Japan, and other countries. Although the ball bearing system inherent in base-isolation systems was proposed by Dr. K. Kito in 1924, only recently have base-isolated structures been proposed and enthusiastically put into practice in Japan. As of November 1994, a total of 79 structure design plans for base-isolated structures have obtained the special permission required in Japan. This paper outlines a safety evaluation guideline for base-isolated structures in Japan.
STUDYING THE DESIGN OF WIND TUNNEL FOR AERODYNAMIC AND AEROACOUSTIC TESTS OF BUILDING STRUCTURES
Directory of Open Access Journals (Sweden)
O. O. Egorychev
2012-11-01
Full Text Available Statement of the problem. In order to study building aerodynamics, a scientific and industrial la-boratory was created at the Moscow State University of Civil Engineering for aerodynamic and aeroacoustic tests of building structures. The main research station in the laboratory was a wind tunnel. This paper describes a design of a wind tunnel to study the aerodynamic and acoustic ef-fects on buildings, structures and their elements.Results and conclusions. Different variants of principal schemes of wind tunnels were examined and developed. Preliminary calculating characteristics of the setup were obtained. The internation-al experienced of aero setup design was used in elaborating the structure. It was developed using numerical modelling and the method of a series of calculation of gas dynamics of an closed sub-sonic wind tunnel being designed. It was found that a modified structure with a 7-degree turn of a nozzle and operating area significantly improves gas dynamics in the operating area.
Heinzel, Johannes; Kemper, Thomas
2015-03-01
Classification approaches for urban areas are mostly of qualitative and semantic nature. They produce interpreted classes similar to those from land cover and land use classifications. As a complement to those classes, quantitative measures directly derived from the image could lead to a metric characterization of the urban area. While these metrics lack of qualitative interpretation they are able to provide objective measure of the urban structures. Such quantitative measures are especially important in rapidly growing cities since, beside of the growth in area, they can provide structural information for specific areas and detect changes. Rustenburg, which serves as test area for the present study, is amongst the fastest growing cities in South Africa. It reveals a heterogeneous face of housing and building structures reflecting social and/or economic differences often linked to the spatial distribution of industrial and local mining sites. Up to date coverage with aerial photographs is provided by aerial surveys in regular intervals. Also recent satellite systems provide imagery with suitable resolution. Using such set of very high resolution images a fully automated algorithm has been developed which outputs metric classes by systematically combining important measures of building structure. The measurements are gained by decomposition of buildings directly from the imagery and by using methods from mathematical morphology. The decomposed building objects serve as basis for the computation of grid statistics. Finally a systematic combination of the single features leads to combined metrical classes. For the dominant urban structures verification results indicate an overall accuracy of at least 80% on the single feature level and 70% for the combined classes.
Flow structures around a gable-roofed building model in tornado-like winds
Yang, Zifeng; Balaramudu, Vasanth; Haan, Fred; Sarkar, Partha; Hu, Hui
2007-11-01
Tornadoes are violently rotating columns of air which are considered as nature's most violent storms. In an average year, 800 ˜ 1000 tornados would occur in the U.S. alone, and cause about 80 deaths (on average), over 1500 injuries, and 850 million worth of property damage. By using the world-largest tornado simulator of Iowa State University, a comprehensive experimental investigation was conducted to characterize the flow structures around a low-rise, gable-roofed building model in tornado-like winds. While pressure taps and force transducers were used to map the pressure distributions around the building model and measure the aerodynamic forces acting on the building model induced by the tornado-like winds, a high-resolution Particle Image Velocimetry (PIV) system was used to conduct detailed flow velocity field measurements around the gable-roofed building model. The ultimate objective of the present study is to quantify the surface winds generated by tornadoes and flow-structure interactions between tornadoes and built environments to assess wind-induced damage with the purpose of mitigating damage and improving public safety.
International Nuclear Information System (INIS)
This paper describes the review structural analysis for the Turbine Building of Olkiluoto 3 NPP (UMA) under finished condition when building is covered with insulated cladding and inside temperatures are maintained by HVAC system. The main aim of the review structural analysis is to ensure the sufficient strength and deformation characteristics of the turbine building structures. The second part of this paper describes the verification structural analysis for the Cooling Water Pump Building of Olkiluoto 3 NPP (UQA). The current verification analysis assesses the validity of the Cooling Water Pump building design for serviceability limit states concentrating on crack width calculations. The introduction of construction time shrinkage joints in the turbine building deletes to the large extent the uneven shrinkage contraction in the concrete substructure. It also enables the uniform temperature expansion of the turbine building structures. The required rebar areas in the cooling water pump building were determined for long term serviceability limit states and for allowable crack widths of 0.13 mm as well as for short term serviceability limit states and for allowable crack widths of 0.26 mm. From the obtained results it can be concluded that more than 95% from the all shell elements in the model of the cooling water pump building fulfill crack width requirements in both long term and short term load conditions with the system reinforcement of two layers of 20 mm rebars with 100 mm pitch in both directions. (author)
Protective system for civil buildings and industrial structures subjected to the seismic risk
Ghica, D.; Grigore, A.; Ionescu, C.
2009-04-01
Romania is a European country with significant seismicity. The most active seismic zone is represented by the Vrancea area, located within the arch of the Carpathians Mountains. Vrancea seismicity is characterized by intermediate depth earthquakes which occur in a narrow epicentral and hypocentral region. During the last 70 years, Romania experienced four strong Vrancea earthquakes: 10 November 1940 (Mw =7.7, 160 km depth), 4 March 1977 (Mw =7.5, 100 km depth), 30 August 1986 (Mw =7.2, 140 km depth), 30 May 30 1990 (Mw =6.9, 80 km depth). The 1977 event was characterized by catastrophic consequences: 1500 casualties and collapsing of 35 high-risk buildings, mostly occurring in Bucharest. The purpose of this paper is to present a protective system designed to be installed in the civil buildings and industrial structures placed in the high seismic regions, and therefore to contribute to the mitigation of the strong earthquake effects on human society. This system proposes an efficient antiseismic protection, respectively shutting down the installations and equipments mounted in the building's infrastructure, which can become extremely dangerous in case of a major earthquake by appearing the possibility of explosions, deflagration, fires, toxic and polluting fluids leakage. The damages are strongly amplified by the fact that, simultaneously, water and electric energy lines distributions are damaged too, making impossible an efficient firemen intervention, for localizing the fire sources. Moreover, the installations of the individual heating stations which operate with open flame increase the risk of explosions inside the buildings during an earthquake. The protective system consists of a seismic switch used for activating through weak-electric-currents of the building's safety systems in case of strong earthquake, especially designed for building's elevators, as well as for moving parts of installations, which require positioning in safety place areas. The originality
Utilization of the Building-Block Approach in Structural Mechanics Research
Rouse, Marshall; Jegley, Dawn C.; McGowan, David M.; Bush, Harold G.; Waters, W. Allen
2005-01-01
In the last 20 years NASA has worked in collaboration with industry to develop enabling technologies needed to make aircraft safer and more affordable, extend their lifetime, improve their reliability, better understand their behavior, and reduce their weight. To support these efforts, research programs starting with ideas and culminating in full-scale structural testing were conducted at the NASA Langley Research Center. Each program contained development efforts that (a) started with selecting the material system and manufacturing approach; (b) moved on to experimentation and analysis of small samples to characterize the system and quantify behavior in the presence of defects like damage and imperfections; (c) progressed on to examining larger structures to examine buckling behavior, combined loadings, and built-up structures; and (d) finally moved to complicated subcomponents and full-scale components. Each step along the way was supported by detailed analysis, including tool development, to prove that the behavior of these structures was well-understood and predictable. This approach for developing technology became known as the "building-block" approach. In the Advanced Composites Technology Program and the High Speed Research Program the building-block approach was used to develop a true understanding of the response of the structures involved through experimentation and analysis. The philosophy that if the structural response couldn't be accurately predicted, it wasn't really understood, was critical to the progression of these programs. To this end, analytical techniques including closed-form and finite elements were employed and experimentation used to verify assumptions at each step along the way. This paper presents a discussion of the utilization of the building-block approach described previously in structural mechanics research and development programs at NASA Langley Research Center. Specific examples that illustrate the use of this approach are
Wandering of the modal parameters in existing building: application to structural health monitoring
Gueguen, Philippe
2012-01-01
Ambient vibrations in building is of increasing interest for applications in mechanical engineering, civil engineering and earthquake engineering. With advances in data acquisition systems (number of measurement points, continuous recording, low-noise instrument) and advances in signal processing algorithms, further and better studies can be conducted on civil engineering structures for evaluating their modal parameters and their physical properties. This study is focused on long- and short-t...
Soil-structure interaction in the Tokamak building of ITER - Influence of the seismic wave pattern
Energy Technology Data Exchange (ETDEWEB)
Beltran, F.; Combescure, D.; Vaz-Romero, A.
2010-07-01
With a design basis earthquake at the level of 0.315 g ZPGA, seismic action is a major concern for the design of the ITER buildings and the main mechanical components. A change in the representation of the seismic motion or in the assumptions for soil-structure interaction may have important technical and financial consequences. As it is known, the ITER building housing the fusion reactor, the Tokamak Complex, has a plan of 120 x 80 m, and it will be built with a base isolation system formed with about 500 steel reinforced neoprene pads. Such a configuration will provide a good isolation against horizontal ground movements, but not against vertical or rocking movements. Therefore, non-vertically incident waves or Rayleigh waves might have some significant contribution to the response of the structure. This contribution could be missed if the common assumption of vertically propagating waves is used in the soil structure interaction (SSI) analyses. In addition, the Tokamak complex is embedded almost 20 m in rock. Normally, the embedment of the foundation will produce some reduction in the seismic input to the building, when compared with the control point input defined at the ground surface. This effect of kinematic interaction due to the embedment of the foundation can also be significant. In this context, the work described in the present paper has been carried out to assess the differences in structural response at the Tokamak Complex that can derive from different assumptions about the seismic wave patterns. Additionally, the effect of foundation embedment on the seismic input actually seen by the building has been investigated.
Aircraft-crash-protected steel reactor building roof structure for the European market
International Nuclear Information System (INIS)
This paper recommends the use of all steel roof structures for the reactor building of European Boiling Water Reactor (BWR) plants. This change would make the advanced US BWR designs more compatible with European requirements. Replacement of the existing concrete roof slab with a sufficiently thick steel plate would eliminate the concrete spelling resulting from a postulated aircraft crash, potentially damaging the drywell head or the spent fuel pool
Soil-structure interaction in the Tokamak building of ITER - Influence of the seismic wave pattern
International Nuclear Information System (INIS)
With a design basis earthquake at the level of 0.315 g ZPGA, seismic action is a major concern for the design of the ITER buildings and the main mechanical components. A change in the representation of the seismic motion or in the assumptions for soil-structure interaction may have important technical and financial consequences. As it is known, the ITER building housing the fusion reactor, the Tokamak Complex, has a plan of 120 x 80 m, and it will be built with a base isolation system formed with about 500 steel reinforced neoprene pads. Such a configuration will provide a good isolation against horizontal ground movements, but not against vertical or rocking movements. Therefore, non-vertically incident waves or Rayleigh waves might have some significant contribution to the response of the structure. This contribution could be missed if the common assumption of vertically propagating waves is used in the soil structure interaction (SSI) analyses. In addition, the Tokamak complex is embedded almost 20 m in rock. Normally, the embedment of the foundation will produce some reduction in the seismic input to the building, when compared with the control point input defined at the ground surface. This effect of kinematic interaction due to the embedment of the foundation can also be significant. In this context, the work described in the present paper has been carried out to assess the differences in structural response at the Tokamak Complex that can derive from different assumptions about the seismic wave patterns. Additionally, the effect of foundation embedment on the seismic input actually seen by the building has been investigated.
International Nuclear Information System (INIS)
In the earthquake response analysis for a rigid and massive structure as a nuclear reactor building, it is important to estimate the effect of soil-structure interaction (SSI) appropriately. In case of strong earthquakes, the nonlinearity, such as the wall-ground separation, the base mat uplift of sliding, makes the behavior of the soil-structure system complex. But, if the nuclear reactor building is embedded in a relatively soft ground with surface layer, the wall-ground separation plays the most important role in the response of soil-structure system. Because, it is expected that the base uplift and slide would be less significant due to the effect of the embedment, and the wall-ground friction is usually neglected in design. But, the nonlinearity of ground may have some effect on the wall-ground separation and the response of the structure. These problems have been studied by use of FEM. Others used joint elements between the ground and the structure which does not resist tensile force. Others studied the effect of wall-ground separation with non-tension springs. But the relationship between the ground condition and the effect of the separation has not been clarified yet. To clarify the effect the analyses by FE model and lumped mass model (sway-rocking model) are performed and compared. The key parameter is the ground profile, namely the stiffness of the side soil
Directory of Open Access Journals (Sweden)
Cilić Aleksandra
2012-01-01
Full Text Available The paper presents global stability comparative analysis of two distinctive structural systems for one 25 - storey high steel building. These are the system with rigid and the system with hinged joint connections between beams and columns in the steel structure. The analysis focuses on the basic structure which was designed only to carry vertical loads, and on the corresponding structure which was stabilized with vertical bracings in the façade walls. Additionally, the paper shows several intermediate steps in the designing of stabilized systems. Static and dynamic design of the relevant structural systems, as well as the control of stress, deformation and stability under the seismic forces of seismic intensity VIII, was done on a computer, on the 3D computation models using Finite Element Method.
Directory of Open Access Journals (Sweden)
Jin Xiaoying
2005-01-01
Full Text Available High-resolution satellite imagery provides an important new data source for building extraction. We demonstrate an integrated strategy for identifying buildings in 1-meter resolution satellite imagery of urban areas. Buildings are extracted using structural, contextual, and spectral information. First, a series of geodesic opening and closing operations are used to build a differential morphological profile (DMP that provides image structural information. Building hypotheses are generated and verified through shape analysis applied to the DMP. Second, shadows are extracted using the DMP to provide reliable contextual information to hypothesize position and size of adjacent buildings. Seed building rectangles are verified and grown on a finely segmented image. Next, bright buildings are extracted using spectral information. The extraction results from the different information sources are combined after independent extraction. Performance evaluation of the building extraction on an urban test site using IKONOS satellite imagery of the City of Columbia, Missouri, is reported. With the combination of structural, contextual, and spectral information, of the building areas are extracted with a quality percentage .
Non-destructive evaluation of timber structures in a historical building of Tiradentes , MG
Directory of Open Access Journals (Sweden)
Luciana Barbosa de Abreu
2013-09-01
Full Text Available Problems related to the durability of wood are commonly found in historical buildings structures. Preservation and conservation resolutions must be adopted, in order to avoid losses and substitutions, which mischaracterize buildings. Non-destructive methods for detecting deterioration should be used in order to substantiate decisions and increase the longevity of historical heritage. This work was carried out in order to perform non-destructive essays to infer about the integrity of a beam and a pillar of the original construction of the Sobrado Ramalho, a historical building of the city of Tiradentes, MG. The equipments utilized were the Stress Wave Timer and resistograph. Samples of the elements were taken for analysis of density. The results showed that, in both structures, to calculate the dynamic modulus of elasticity, there was no significant difference for the application of stress wave timer on the alignments studied. There was no significant difference between the directions of application of the resistograph on the pillar, due to its apparent entirety and regular sessions, practically square, and to not being loaded eccentrically. In the case of the beam, there was significant difference, presumably because it has cracks in its traction line. The equipments, unknown by professionals of heritage conservation allow promising methodologies for inspection of timber structures in service.
Influence of soil–structure interaction on seismic collapse resistance of super-tall buildings
Mengke Li; Xiao Lu; Xinzheng Lu; Lieping Ye
2014-01-01
Numerous field tests indicate that the soil–structure interaction (SSI) has a significant impact on the dynamic characteristics of super-tall buildings, which may lead to unexpected structural seismic responses and/or failure. Taking the Shanghai Tower with a total height of 632 m as the research object, the substructure approach is used to simulate the SSI effect on the seismic responses of Shanghai Tower. The refined finite element (FE) model of the superstructure of Shanghai Tower and the ...
Hanwell, Marcus; Hutchison, Geoffrey
2009-03-01
The Avogadro project is a free, open source approach to building chemical structures. It has integrated analysis, and three-dimensional visualization capabilities. Avogadro also uses external packages to perform quantum structure calculations. The work presented here illustrates a novel approach to working with the results of quantum calculations by visualizing possible molecular orbitals and allowing the user to select orbitals of interest. The Avogadro program allows the user to prepare new jobs for various quantum codes such as GAMESS-US, Q-Chem, Gaussian and Molpro. Due to the plugin based nature of the Avogadro project many specialized options can be added, such as raytracing the electronic structure of the molecule to produce high quality output, building carbon nanotube structures, or designing solid-state structures. Avogadro is already being used by educators and researchers. Due to the free and open source nature of the project, it can be readily downloaded and used by all students in and out of the classroom. It can also be tailored to particular institutions and/or courses.
Chirality-Assisted Electronic Cloaking of Confined States in Bilayer Graphene
Gu, Nan; Rudner, Mark; Levitov, Leonid
2011-10-01
We show that the strong coupling of pseudospin orientation and charge carrier motion in bilayer graphene has a drastic effect on transport properties of ballistic p-n-p junctions. Electronic states with zero momentum parallel to the barrier are confined under it for one pseudospin orientation, whereas states with the opposite pseudospin tunnel through the junction totally uninfluenced by the presence of confined states. We demonstrate that the junction acts as a cloak for confined states, making them nearly invisible to electrons in the outer regions over a range of incidence angles. This behavior is manifested in the two-terminal conductance as transmission resonances with non-Lorentzian, singular peak shapes. The response of these phenomena to a weak magnetic field or electric-field-induced interlayer gap can serve as an experimental fingerprint of electronic cloaking.
Comment on "Characterization of an acoustic spherical cloak", Inverse Problems 31(3):035001, 2015
Norris, A N
2015-01-01
The paper [1] considers a spherical cloak described by three radially varying acoustical quantities. For a given radial mass density in the cloak the question posed is whether the remaining two parameters, tangential density and compressibility, are uniquely determined. A method is proposed in [1] to solve this inverse question based upon the solution of a Riemann-Hilbert problem involving spectral properties of a one-dimensional inhomogeneous Schr\\"odinger equation. However, no constructive examples of the solution procedure are given. This comment provides explicit solutions for any radial mass density that conforms with the requirements of transformation acoustics [2]. A valid form of the compatibility condition [1, eq. (22)] for $n=0$ is derived.
Fick's second law transformed: one path to cloaking in mass diffusion
Guenneau, S.; Puvirajesinghe, T. M.
2013-01-01
Here, we adapt the concept of transformational thermodynamics, whereby the flux of temperature is controlled via anisotropic heterogeneous diffusivity, for the diffusion and transport of mass concentration. The n-dimensional, time-dependent, anisotropic heterogeneous Fick's equation is considered, which is a parabolic partial differential equation also applicable to heat diffusion, when convection occurs, for example, in fluids. This theory is illustrated with finite-element computations for a liposome particle surrounded by a cylindrical multi-layered cloak in a water-based environment, and for a spherical multi-layered cloak consisting of layers of fluid with an isotropic homogeneous diffusivity, deduced from an effective medium approach. Initial potential applications could be sought in bioengineering. PMID:23536540
Fick's Second Law Transformed: One Path to Cloaking in Mass Diffusion
Guenneau, Sebastien
2013-01-01
Here, we adapt the concept of transformational thermodynamics, whereby the flux of temperature is controlled via anisotropic heterogeneous diffusivity, for the diffusion and transport of mass concentration. The n-dimensional, time-dependent, anisotropic heterogeneous Fick's equation is considered, which is a parabolic partial differential equation also applicable to heat diffusion, when convection occurs, for example in fluids. This theory is illustrated with finite element computations for a liposome particle surrounded by a cylindrical multilayered cloak in a water-based environment, and for a spherical multilayered cloak consisting of layers of fluid with an isotropic homogeneous diffusivity, deduced from an effective medium approach. Initial potential applications could be sought in bio-engineering.
Lipid-insertion enables targeting functionalization of erythrocyte membrane-cloaked nanoparticles
Fang, Ronnie H.; Hu, Che-Ming J.; Chen, Kevin N. H.; Luk, Brian T.; Carpenter, Cody W.; Gao, Weiwei; Li, Shulin; Zhang, Dong-Er; Lu, Weiyue; Zhang, Liangfang
2013-09-01
RBC membrane-cloaked polymeric nanoparticles represent an emerging nanocarrier platform with extended circulation in vivo. A lipid-insertion method is employed to functionalize these nanoparticles without the need for direct chemical conjugation. Insertion of both folate and the nucleolin-targeting aptamer AS1411 shows receptor-specific targeting against model cancer cell lines.RBC membrane-cloaked polymeric nanoparticles represent an emerging nanocarrier platform with extended circulation in vivo. A lipid-insertion method is employed to functionalize these nanoparticles without the need for direct chemical conjugation. Insertion of both folate and the nucleolin-targeting aptamer AS1411 shows receptor-specific targeting against model cancer cell lines. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr03064d