scholarly journals Effect of Surface Error Distribution and Aberration on Electromagnetic Performance of a Reflector Antenna

2019 ◽  
Vol 2019 ◽  
pp. 1-15
Author(s):  
Binbin Xiang ◽  
Congsi Wang ◽  
Peiyuan Lian
Keyword(s):  
Large Scale ◽  
Spherical Aberration ◽  
Reflector Antenna ◽  
Error Distribution ◽  
Simple Manner ◽  
Optical Aberration ◽  
Antenna Performance ◽  
Surface Distortions ◽  
Electromagnetic Performance ◽  
Effect Of Surface

In this paper, a method based on the Zernike distribution and the optical aberration is proposed to investigate the effects of the distribution characteristics of surface distortions of a reflector antenna on its electromagnetic performance (EMP). For large-scale errors, an analytical model is introduced to describe the arbitrary distortions, based on the orthogonal Zernike polynomials. The effects of error distribution described by the Zernike series on typical EMP are analyzed. The numerical results indicate that the distortions in the distribution feature of defocus or spherical aberration have a greater impact on gain, and the distribution feature of tilt or coma mainly influences boresight offset; the distribution feature of defocus, astigmatism, and spherical aberration has a greater impact on sidelobe levels. The results indicate that the beam contour patterns are related to the distribution forms of distortions and are similar with the same aberration feature. On the basis of the Seidel aberration, the relationships between typical EMP and the aberration coefficient are presented. Based on these, the error profile of the primary influence and the approximate feature of EMP can be determined, and the antenna performance can be predicted in a simple manner.

Simultaneous 3D position sensing by means of large-scale spherical aberration of lens and Hough transform technique

2005 ◽  
Author(s):  
Yasuji Seko ◽  
Yasuyuki Saguchi ◽  
Yoshinori Yamaguchi ◽  
Hiroyuki Hotta ◽  
Kazumasa Murai ◽  
...  
Keyword(s):  
Hough Transform ◽  
Large Scale ◽  
Spherical Aberration ◽  
Position Sensing

Towards Rapid Redesign: Decomposition Patterns for Large-Scale and Complex Redesign Problems

2005 ◽  
Author(s):  
Li Chen ◽  
Simon Li ◽  
Ashish Macwan
Keyword(s):  
Quantum Information ◽  
Large Scale ◽  
Pattern Analysis ◽  
Intrinsic Properties ◽  
Simple Manner ◽  
Pattern Synthesis ◽  
Solution Approach ◽  
Problem Types ◽  
Pattern Quantification

In an effort to develop a decomposition-based rapid redesign methodology, this paper introduces the basis of such a methodology on decomposition patterns for a general redesign problem that is computation-intensive and simulation-complex. In particular, through pattern representation and quantification, this paper elaborates the role and utility of the decomposition patterns in decomposition-based rapid redesign. In pattern representation, it shows how a decomposition pattern can be used to capture and portray the intrinsic properties of a redesign problem. Thus, through pattern synthesis, the collection of proper decomposition patterns allows one to effectively represent in a concise form the complete body of redesign knowledge covering all redesign problem types. In pattern quantification, it shows how a decomposition pattern can be used to extract and convey the quantum information of a redesign problem using the pattern characteristics. Thus, through pattern analysis, the formulation of an index incorporating two redesign metrics allows one to efficiently predict in a simple manner the amount of potential redesign effort for a given redesign problem. This work represents a breakthrough in extending the decomposition-based solution approach to computational redesign problems.

Effects of Deposits on Film Cooling of a Vane Endwall Along the Pressure Side

2008 ◽  
Vol 130 (4) ◽  
Author(s):  
N. Sundaram ◽  
M. D. Barringer ◽  
K. A. Thole
Keyword(s):  
Film Cooling ◽  
Large Scale ◽  
Secondary Flows ◽  
Pressure Side ◽  
Surface Deposition ◽  
Hot Gas ◽  
Turbine Vane ◽  
Adiabatic Effectiveness ◽  
Film Cooling Holes ◽  
Effect Of Surface

Film cooling is influenced by surface roughness and depositions that occur from contaminants present in the hot gas path, whether that film cooling occurs on the vane itself or on the endwalls associated with the vanes. Secondary flows in the endwall region also affect the film-cooling performance along the endwall. An experimental investigation was conducted to study the effect of surface deposition on film cooling along the pressure side of a first-stage turbine vane endwall. A large-scale wind tunnel with a turbine vane cascade was used to perform the experiments. The vane endwall was cooled by an array of film-cooling holes along the pressure side of the airfoil. Deposits having a semielliptical shape were placed along the pressure side to simulate individual row and multiple row depositions. Results indicated that the deposits lowered the average adiabatic effectiveness levels downstream of the film-cooling rows by deflecting the coolant jets toward the vane endwall junction on the pressure side. Results also indicated that there was a steady decrease in adiabatic effectiveness levels with a sequential increase in the number of rows with the deposits.

scholarly journals Thickness-Weighted Mean Theory for the Effect of Surface Gravity Waves on Mean Flows in the Upper Ocean

2012 ◽  
Vol 42 (5) ◽  
pp. 725-747 ◽  
Author(s):  
Hidenori Aiki ◽  
Richard J. Greatbatch
Keyword(s):  
Gravity Waves ◽  
Large Scale ◽  
Turbulent Viscosity ◽  
Residual Effect ◽  
Surface Gravity ◽  
Upper Ocean ◽  
Weighted Mean ◽  
Surface Gravity Waves ◽  
Viscosity Term ◽  
Effect Of Surface

Abstract The residual effect of surface gravity waves on mean flows in the upper ocean is investigated using thickness-weighted mean (TWM) theory applied in a vertically Lagrangian and horizontally Eulerian coordinate system. Depth-dependent equations for the conservation of volume, momentum, and energy are derived. These equations allow for (i) finite amplitude fluid motions, (ii) the horizontal divergence of currents, and (iii) a concise treatment of both kinematic and viscous boundary conditions at the sea surface. Under the assumptions of steady and monochromatic waves and a uniform turbulent viscosity, the TWM momentum equations are used to illustrate the pressure- and viscosity-induced momentum fluxes through the surface, which are implicit in previous studies of the wave-induced modification of the classical Ekman spiral problem. The TWM approach clarifies, in particular, the surface momentum flux associated with the so-called virtual wave stress of Longuet-Higgins. Overall, the TWM framework can be regarded as an alternative to the three-dimensional Lagrangian mean framework of Pierson. Moreover, the TWM framework can be used to include the residual effect of surface waves in large-scale circulation models. In specific models that carry the TWM velocity appropriate for advecting tracers as their velocity variable, the turbulent viscosity term should be modified so that the viscosity acts only on the Eulerian mean velocity.

Solar panel scattering effects on reflector antenna performance

1997 ◽  
Vol 33 (8) ◽  
pp. 650 ◽  
Author(s):  
S.U. Hwu ◽  
L.A. Johnson ◽  
R.J. Panneton
Keyword(s):  
Reflector Antenna ◽  
Solar Panel ◽  
Antenna Performance ◽  
Scattering Effects

The Design and Implementation of Matlab Simulation in Optical Aberration

2014 ◽  
Vol 575 ◽  
pp. 541-544
Author(s):  
Zhen Hua Lao
Keyword(s):  
Programming Language ◽  
Spherical Aberration ◽  
Simulation Algorithm ◽  
Matlab Simulation ◽  
Parametric Variation ◽  
Design And Implementation ◽  
Optical Aberration ◽  
Aberration Theory

In the teaching of optical courses, the aberration knowledge is abstract and students often feel it difficult to understand. According to this phenomenon, a new simulation algorithm, which is based on the analysis of chromatic and spherical aberration theory, is described in this paper; with Matlab as the programming language, the emulation programs of chromatic and spherical aberration are designed and the simulation figures are presented, from which the effect of parametric variation on aberration can be shown vividly and intuitively. And for students, this will be helpful in the mastery of aberration knowledge.

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