NUMERICAL STUDY OF MORPHOLOGICAL CHANGES BY FAR-FIELD TSUNAMI IMPACTS

In this article, we present an experimental and numerical study of novel optical properties of two-dimensional dielectric photonic crystals (PCs) which exhibit negative refraction. We investigate two mechanisms which utilize the band structure of the PC to generate a negative effective index of refraction (n eff <0) and demonstrate the negative refraction experimentally. To the isotropic extend of n eff , different PC slab structures are employed to focus the radiation of a point source. It is shown experimentally that the PC can generate an image of the source with subwavelength resolution in the vicinity of the PC interface. Using a different PC, one can also obtain a far field focusing. In the latter case, we explicitly show the flat lens behavior of the structure. These examples indicate that PC-based lenses can surpass limitations of conventional lenses and lead to novel optics applications.

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Numerical study of terahertz circular polarized substrate lens dipole antennas for polarization sensitive detectors

International Journal of Microwave and Wireless Technologies ◽

10.1017/s1759078715000380 ◽

2015 ◽

Vol 8 (3) ◽

pp. 623-631

Author(s):

Amna Mir ◽

Junsheng Yu ◽

Xiaodong Chen ◽

Ishtiaq Ahmad

Keyword(s):

Numerical Study ◽

Wide Band ◽

Cd Spectroscopy ◽

Internal Reflection ◽

Point Of View ◽

Far Field ◽

Dipole Antennas ◽

Planar Antennas ◽

Field Patterns ◽

Feeding Structure

Wide band circular polarized (CP) antennas behind extended hemispherical lenses suitable for polarization sensitive THz detector and wireless communication have been designed and characterized using numerical simulation. Two novel, compact and CP dipole antennas are designed and studied for this purpose. CP property of planar antennas is achieved by geometrical modifications of antennas without any complicated feeding structure. Due to compact dimensions, wideband performance and CP behavior, these designs have applications in circular dichroism (CD) spectroscopy and terahertz detectors. This numerical study deals with polarization diversity with substrate lens, effect of off axis displacement on CP behavior of lens antenna which determines number of pixels for any application, far field patterns variation due to lens's internal reflection, directivity variation attributed to internal reflection and losses. Radiation efficiency variation of antenna by antenna dimensions is also studied carefully to design appropriate lens from application's point of view. Off axis performance of antenna on hemisphere lens is also studied and redesigning of antenna by some geometric modification has been carried out to improve far field patterns.

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Numerical Study of the Seismic Efficiency of Buckling-Restrained Braces for Near and Far-Fault Inputs

The Open Civil Engineering Journal ◽

10.2174/1874149501509010281 ◽

2015 ◽

Vol 9 (1) ◽

pp. 281-294

Author(s):

G.L. Palazzo ◽

P. Martín ◽

F. Calderón ◽

V. Roldán ◽

F. López-Almansa

Keyword(s):

Dynamic Response ◽

Numerical Study ◽

Experimental Studies ◽

Time Interval ◽

Short Time Interval ◽

Far Field ◽

Near Fault ◽

Buckling Restrained Braces ◽

Seismic Records ◽

Far Fault

Buckling-restrained braces are commonly installed in building structures as concentric diagonal or chevron braces to protect the main construction from seismic actions. These elements have shown repeatedly their usefulness for reducing the seismic response, both from theoretical and experimental studies; and a number of practical applications have been reported. However, seismic records with near-fault effects possess special characteristics that might impair the performance of these devices, similarly as what occurs in base isolation; about energy issues, in such records (containing strong velocity pulses) the energy is delivered in a short time interval, thus being difficult to be absorbed. This work presents a numerical study regarding the performance of buckling-restrained braces under three types of seismic records: cortical far-field, subductive far-field and near-field (i.e. containing velocity pulses). The study is carried out on a symmetric 4-story steel moment-resisting unbraced frame that was tested at the E-defense laboratory, Japan; the dynamic response of such unbraced bare frame is numerically simulated, obtaining a satisfactory agreement. The same numerical model is used to describe the 2-D dynamic behavior of the steel frame equipped with buckling-restrained braces. The inputs are three series of ten ground motion records; each of these series belongs to one of the three aforementioned types. The average responses for each of the three types of inputs are compared; the obtained results show that the buckling-restrained braces are able to reduce the dynamic response of the frame and that no significant differences can be observed among the efficiency for far-fault and near- fault records.

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Correction to “Light Dependent Morphological Changes Can Tune Light Absorption in Iridescent Plant Chloroplasts: A Numerical Study Using Biologically Realistic Data”

ACS Photonics ◽

10.1021/acsphotonics.1c01621 ◽

2021 ◽

Author(s):

Miguel A. Castillo ◽

William P. Wardley ◽

Martin Lopez-Garcia

Keyword(s):

Light Absorption ◽

Numerical Study ◽

Morphological Changes ◽

Realistic Data

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Far Field Optical Properties of a Monolayer of SiO2 Spheres and Small Au Nanoparticles

MRS Advances ◽

10.1557/adv.2019.128 ◽

2018 ◽

Vol 3 (64) ◽

pp. 3917-3923 ◽

Cited By ~ 1

Author(s):

A. Santos Gómez ◽

A. L. González

Keyword(s):

Numerical Study ◽

Normal Incidence ◽

Dipole Approximation ◽

Silica Spheres ◽

Far Field ◽

Approximation Model ◽

Au Nps ◽

Transmission And Absorption ◽

Sio2 Spheres ◽

Hexagonal Closed Packed

ABSTRACTHere, we present a numerical study of the far field optical response of a monolayer composed by an hexagonal closed packed array of SiO2 spheres with a single Au NP at each interstitial position. The Optical Efficiencies, Reflection, Transmission and Absorption at normal incidence, were calculated using Discrete Dipole Approximation model extended to periodic targets. In order to consider different amounts of loads of Au NPs per unit of area in the monolayer, we have fixed the diameter of Au NPs (9 nm) and varied the diameter of the SiO2 spheres. The numerical calculations indicate that Au-SiO2 composite monolayers can absorb and scatter the incident electromagnetic wave, as the load of Au NPs increases the monolayer becomes less transparent to light and the spectra are red-shifted. The profile of the absorption spectrum of the Au-SiO2 composite monolayer is very similar to that of a Au NPs monolayer (composite monolayer without the Silica spheres) but less intense, presumably because the Silica spheres screen the coupling of the Localized Surface Plasmons of Au NPs.

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Numerical Study on the Longitudinal Response Characteristics of Utility Tunnel under Strong Earthquake: A Case Study

Advances in Civil Engineering ◽

10.1155/2020/8813303 ◽

2020 ◽

Vol 2020 ◽

pp. 1-12

Author(s):

Guoyi Tang ◽

Yumei Fang ◽

Yi Zhong ◽

Jie Yuan ◽

Bin Ruan ◽

...

Keyword(s):

Seismic Response ◽

Strong Earthquake ◽

Numerical Study ◽

Soft Soil ◽

Near Field ◽

Element Model ◽

Far Field ◽

Response Characteristics ◽

Longitudinal Response ◽

Utility Tunnel

In this paper, the longitudinal seismic response characteristics of utility tunnel subjected to strong earthquake was investigated based on a practical utility tunnel project and numerical method. Firstly, the generalized response displacement method (GRDM) that was used to conduct this study was reviewed briefly. Secondly, the information of the referenced engineering and the finite element model was introduced in detail, where a novel method to model the joints between utility tunnel segments was presented. Thirdly, a series of seismic response of the utility tunnel were provided, including inner force and intersegment opening width. The results showed that (i) the seismic response of the utility tunnel under far-field earthquake may be remarkable and even higher than that under near-field earthquake; (ii) sharp variation of response may occur at the interface between “soft” soil and “hard” soil, and the variation under far-field earthquake could be much more significant. This research provides a reference for the scientific study and design of relevant engineering.

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SH-wave generation by dislocation sources—A numerical study

Bulletin of the Seismological Society of America ◽

10.1785/bssa0690010001 ◽

1979 ◽

Vol 69 (1) ◽

pp. 1-15 ◽

Cited By ~ 1

Author(s):

Robert B. Herrmann

Keyword(s):

Real Axis ◽

Numerical Study ◽

Numerical Technique ◽

Far Field ◽

Sh Wave ◽

The Real ◽

Relative Contribution ◽

Time Histories ◽

Point Dislocation ◽

Dislocation Sources

abstract A numerical technique is presented for attaining the SH-wave contribution to tangential displacements due to point dislocation sources in a plane layered Earth. The method uses contour integration in the complex k-plane and includes the contribution of branch line integrals along the real and imaginary axes of the k-plane as well as poles along the real axis. Examples are provided to illustrate the effect of neglecting the P-SV contribution to tangential displacements, the effect of improper truncation in estimating far-field time histories, as well as the relative contribution of the various singularities in the complex k-plane to the solution.

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Numerical Study of Wave Overtopping Based on Local Method of Approximate Particular Solution Method

Advances in Mechanical Engineering ◽

10.1155/2014/541717 ◽

2014 ◽

Vol 6 ◽

pp. 541717

Author(s):

Su Jingbo ◽

Zhu Feng ◽

Geng Ying ◽

Ni Xingye

Keyword(s):

Surface Wave ◽

Smooth Surface ◽

Numerical Study ◽

Morphological Changes ◽

Average Error ◽

Physical Model Test ◽

Slope Ratio ◽

Local Method ◽

Wave Overtopping ◽

Particular Solution

In order to study the wave overtopping process, this paper establishes a two-dimensional numerical wave flume based on a meshless algorithm, local method of approximate particular solution (the LMAPS method), and the technology of momentum source wave. It calculates the climbing and overtopping process under regular waves on a typical slope, results of which are more consistent with the physical model test results. Finally, wave action simulation is carried out on six different structural forms of wave walls (vertical wave wall, 1/4 arc wave wall, reversed-arc wave wall, smooth surface wave wall with 1: 3 slope ratio, smooth surface wave wall with 1: 1.5 slope ratio and stepped surface wave wall with 1: 1.5 slope ratio). Numerical results of the simulation accurately describe the wave morphological changes in the interaction of waves and different structural forms of wave walls, in which, average error of wave overtopping is roughly 6.2% compared with the experimental values.

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On the critical free-surface flow over localised topography

Journal of Fluid Mechanics ◽

10.1017/jfm.2017.639 ◽

2017 ◽

Vol 832 ◽

pp. 73-96 ◽

Cited By ~ 2

Author(s):

J. S. Keeler ◽

B. J. Binder ◽

M. G. Blyth

Keyword(s):

Nonlinear Problem ◽

Numerical Study ◽

Bottom Topography ◽

Solution Space ◽

Boundary Integral ◽

Steady Solution ◽

Far Field ◽

Algebraic Decay ◽

Fully Nonlinear ◽

Fkdv Equation

Flow over bottom topography at critical Froude number is examined with a focus on steady, forced solitary wave solutions with algebraic decay in the far field, and their stability. Using the forced Korteweg–de Vries (fKdV) equation the weakly nonlinear steady solution space is examined in detail for the particular case of a Gaussian dip using a combination of asymptotic analysis and numerical computations. Non-uniqueness is established and a seemingly infinite set of steady solutions is uncovered. Non-uniqueness is also demonstrated for the fully nonlinear problem via boundary-integral calculations. It is shown analytically that critical flow solutions have algebraic decay in the far field both for the fKdV equation and for the fully nonlinear problem and, moreover, that the leading-order form of the decay is the same in both cases. The linear stability of the steady fKdV solutions is examined via eigenvalue computations and by a numerical study of the initial value fKdV problem. It is shown that there exists a linearly stable steady solution in which the deflection from the otherwise uniform surface level is everywhere negative.

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