Simulation of the Electromagnetic Far-Field Scattered by an Object Based on Measurements of the Near-Field on a Scanning Segment in the Scalar Two-Dimensional Case

2021 ◽  
Author(s):  
Nicolay P. Balabukha ◽  
Denis A. Konyaev ◽  
Natalia E. Shapkina ◽  
Ksenia M. Shitikova
Keyword(s):  
Near Field ◽  
Dimensional Case ◽  
Far Field ◽  
Two Dimensional ◽  
Object Based

scholarly journals Predicting Far-Field Noise Generated by a Landing Gear Using Multiple Two-Dimensional Simulations

2019 ◽  
Vol 9 (21) ◽  
pp. 4485
Author(s):  
Sultan Alqash ◽  
Sharvari Dhote ◽  
Kamran Behdinan
Keyword(s):  
Cross Sections ◽  
Near Field ◽  
Computational Cost ◽  
Numerical Data ◽  
Landing Gear ◽  
Design Stage ◽  
Far Field ◽  
Two Dimensional ◽  
Acoustic Analogy ◽  
Field Noise

In this paper, a new approach is proposed to predict the far-field noise of a landing gear (LG) based on near-field flow data obtained from multiple two-dimensional (2D) simulations. The LG consists of many bluff bodies with various shapes and sizes. The analysis begins with dividing the LG structure into multiple 2D cross-sections (C-Ss) representing different configurations. The C-Ss locations are selected based on the number of components, sizes, and geometric complexities. The 2D Computational Fluid Dynamics (CFD) analysis for each C-S is carried out first to obtain the acoustic source data. The Ffowcs Williams and Hawkings acoustic analogy (FW-H) is then used to predict the far-field noise. To compensate for the third dimension, a source correlation length (SCL) is assumed based on a perfectly correlated flow. The overall noise of the LG is calculated as the incoherent sum of the predicted noise from all C-Ss. Flow over a circular cylinder is then studied to examine the effect of the 2D CFD results on the predicted noise. The results are in good agreement with reported experimental and numerical data. However, the Strouhal number (St) is over-predicted. The proposed approach provides a reasonable estimation of the LG far-field noise at a low computational cost. Thus, it has the potential to be used as a quick tool to predict the far-field noise from an LG during the design stage.

Prediction of Rail and Bridge Noise in Near- and Far-Field: A Combined 2.5-Dimensional and Two-Dimensional Method

2016 ◽  
Vol 139 (1) ◽  
Author(s):  
X. D. Song ◽  
Q. Li ◽  
D. J. Wu
Keyword(s):  
Interaction Analysis ◽  
Near Field ◽  
Three Dimensional ◽  
Shielding Effect ◽  
Far Field ◽  
Acoustic Model ◽  
Two Dimensional ◽  
Box Girder ◽  
Total Noise ◽  
Field Noise

Bridge noise and rail noise induced by passing trains should be included while estimating low- and medium-frequency (20–1000 Hz) noise in railway viaducts. However, the prediction of bridge noise and rail noise using a three-dimensional (3D) acoustic model is not efficient, especially for far-field points. In this study, a combined 2.5-dimensional (2.5D) and two-dimensional (2D) method is proposed to predict bridge noise and rail noise in both the near- and far-field. First, the near-field noise is obtained by combining the 2.5D acoustic model and a 3D vehicle–track–bridge interaction analysis. Then, the 2D method is used to estimate the attenuation of bridge noise and rail noise in the far-field, and the accuracy is validated through comparison with the 2.5D method. Third, the near-field points are treated as reference sources, and the noise at far-field points is predicted by combining the 2.5D and 2D methods. Finally, the proposed method is used to predict the bridge noise and rail noise for a box girder and a U-shaped girder. The spatial distribution of the bridge noise and rail noise is investigated. Generally, the rail noise is dominant above the bridge, and the bridge noise has a larger contribution to the total noise beneath the bridge. The rail noise from the U-shaped girder is much smaller than that from the box girder due to the shielding effect of the webs.

scholarly journals Two-dimensional Near-field and Far-field Imaging of a Ne-like Ar Capillary Discharge Table-top Soft X-ray Laser

1998 ◽  
Vol 9 (12) ◽  
pp. 55
Author(s):  
C. H. Moreno ◽  
M. C. Marconi ◽  
V. N. Shlyaptsev ◽  
B. R. Benware ◽  
C. D. Macchietto ◽  
...  
Keyword(s):  
Near Field ◽  
Capillary Discharge ◽  
Far Field ◽  
Two Dimensional ◽  
X Ray ◽  
Field Imaging

scholarly journals Two-dimensional near-field and far-field imaging of a Ne-like Ar capillary discharge table-top soft-x-ray laser

1998 ◽  
Vol 58 (2) ◽  
pp. 1509-1514 ◽  
Author(s):  
C. H. Moreno ◽  
M. C. Marconi ◽  
V. N. Shlyaptsev ◽  
B. R. Benware ◽  
C. D. Macchietto ◽  
...  
Keyword(s):  
Near Field ◽  
Capillary Discharge ◽  
Far Field ◽  
Two Dimensional ◽  
X Ray ◽  
Field Imaging

NEAR FIELD AND FAR FIELD EFFECTS IN THE TAGUCHI-OPTIMIZED DESIGN OF AN InP/GaAs-BASED DOUBLE WAFER-FUSED MQW LONG-WAVELENGTH VERTICAL-CAVITY SURFACE-EMITTING LASER

2012 ◽  
Vol 21 (01) ◽  
pp. 1250006 ◽  
Author(s):  
P. S. MENON ◽  
K. KANDIAH ◽  
J. S. MANDEEP ◽  
S. SHAARI ◽  
P. R. APTE
Keyword(s):  
Orthogonal Array ◽  
Near Field ◽  
Fine Tuning ◽  
Design Parameters ◽  
Field Pattern ◽  
Cavity Surface ◽  
Far Field ◽  
Two Dimensional ◽  
Long Wavelength ◽  
Field Effects

Long-wavelength VCSELs (LW-VCSEL) operating in the 1.55 μm wavelength regime offer the advantages of low dispersion and optical loss in fiber optic transmission systems which are crucial in increasing data transmission speed and reducing implementation cost of fiber-to-the-home (FTTH) access networks. LW-VCSELs are attractive light sources because they offer unique features such as low power consumption, narrow beam divergence and ease of fabrication for two-dimensional arrays. This paper compares the near field and far field effects of the numerically investigated LW-VCSEL for various design parameters of the device. The optical intensity profile far from the device surface, in the Fraunhofer region, is important for the optical coupling of the laser with other optical components. The near field pattern is obtained from the structure output whereas the far-field pattern is essentially a two-dimensional fast Fourier Transform (FFT) of the near-field pattern. Design parameters such as the number of wells in the multi-quantum-well (MQW) region, the thickness of the MQW and the effect of using Taguchi's orthogonal array method to optimize the device design parameters on the near/far field patterns are evaluated in this paper. We have successfully increased the peak lasing power from an initial 4.84 mW to 12.38 mW at a bias voltage of 2 V and optical wavelength of 1.55 μm using Taguchi's orthogonal array. As a result of the Taguchi optimization and fine tuning, the device threshold current is found to increase along with a slight decrease in the modulation speed due to increased device widths.

scholarly journals Localizing nanoscale objects using nanophotonic near-field transducers

Nanophotonics ◽  
2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Tom A. W. Wolterink ◽  
Robin D. Buijs ◽  
Giampiero Gerini ◽  
A. Femius Koenderink ◽  
Ewold Verhagen
Keyword(s):  
Reference Data ◽  
Near Field ◽  
Metallic Film ◽  
Far Field ◽  
Two Dimensional ◽  
Scattering Pattern ◽  
Field Environment ◽  
Field Response ◽  
Nanoscale Object ◽  
Nanophotonic Structures

Abstract We study how nanophotonic structures can be used for determining the position of a nearby nanoscale object with subwavelength accuracy. Through perturbing the near-field environment of a metasurface transducer consisting of nano-apertures in a metallic film, the location of the nanoscale object is transduced into the transducer’s far-field optical response. By monitoring the scattering pattern of the nanophotonic near-field transducer and comparing it to measured reference data, we demonstrate the two-dimensional localization of the object accurate to 24 nm across an area of 2 × 2 μm. We find that adding complexity to the nanophotonic transducer allows localization over a larger area while maintaining resolution, as it enables encoding more information on the position of the object in the transducer’s far-field response.

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