Cubic Spline Interpolation Technique Research Articles

A Cylindrical Equivalent Source-Based Physical Optics Method for Rapid Analysis of Airborne Radomes

The physical optics (PO) method treats the outer surface of airborne radomes in front of antennas as a secondary source region when analyzing the electromagnetic performance. The effective reduction of the secondary source region can significantly improve the computational efficiency, which is helpful for the rapid analysis and design of airborne radomes. In this paper, we present a cylindrical equivalent source-based PO method by introducing an antenna radiation cylinder that can cover the main near-field radiation characteristics of the antenna. The cubic-spline interpolation technique is used to standardize the solution method for the boundary of the cylindrical equivalent source of different antenna-radome systems. The results of a tangent-ogival radome verify the validity of the proposed method. Compared with the conical equivalent source-based PO method, the proposed method improves the efficiency by 71.83%. It can be applied to airborne antenna-radome systems with antenna diameters of 12.14 times of wavelength and above, using 10% as the error threshold.

Determination of available transfer capability by means of Ralston's method incorporating cubic-spline interpolation technique

This paper presents a fast and accurate method to determine the power transfer so-called the available transfer capability (ATC). The methodology utilizes the cubic-spline interpolation technique that is incorporated into the Ralston's method in order to provide fast and accurate assessment of ATC. The Ralston's method is used to predict the two trajectory points of voltage magnitude (U), power flow (S), and maximum generator rotor angle difference (Δδ). Then, the cubic-spline interpolation technique is used to accurately trace the P-U, P-S, or P-Δδ curves between two points of trajectory. The P-U, P-S, and P-Δδ curves represent as the variations of voltage magnitude, power flow and maximum generator rotor angle difference due to the increase of power transfer or ATC. The actual value of ATC is then determined when either the voltage magnitude limit, power flow limit or generator rotor angle difference limit intersects the curve. The effectiveness of the proposed method is verified by referring to the results of ATC for a case study of 2737-Polish system and 39-New England bus system. The proposed method gives a satisfactorily accurate and fast computation of ATC as compared to recursive AC power flow method. Copyright © 2010 John Wiley & Sons, Ltd.

Image Compression and Reconstruction using Cubic Spline Interpolation Technique

A new dimension of image compression using random pixels of irregular sampling and image reconstruction using cubic-spline interpolation techniques proposed in this paper. It also covers the wide field of multimedia communication concerned with multimedia messaging (MMS) and image transfer through mobile phones and tried to find a mechanism to transfer images with minimum bandwidth requirement. This method would provide a better efficiency both in pixel reconstruction and color reproduction. The discussion covers theoretical techniques of random pixel selection, transfer and implementation of efficient reconstruction with cubic spline interpolation.

Kinematic wave modeling of overland flow using characteristics method with cubic-spline interpolation

Use of characteristics method integrated with cubic-spline interpolation technique (CSMOC scheme) for computation of one-dimensional and two-dimensional kinematic overland flow has been examined in this study. The characteristic trajectory is allowed to fall on space line and time line for interpolating the corresponding values at the foot of trajectory in terms of neighboring grid points. The effects of different endpoint constraints on use of cubic-spline interpolation are investigated. As far as accuracy and simplicity are concerned, the not-a-knot constraint could be a better choice. Three hypothetical examples are used to examine the capabilities of CSMOC scheme through the comparison with the analytical solution and the well-known Preissmann scheme. Some degrees of numerical diffusion and numerical oscillation, attenuating and overestimating the peak discharge, are induced by the Preissmann scheme. In contrast, the CSMOC scheme gives convincing results for the kinematic overland flow computations.

Fast evaluation of available transfer capability using cubic-spline interpolation technique

This paper presents a new computationally fast and accurate method for evaluating available transfer capability (ATC) based on a curve fitting technique so-called as the cubic-spline interpolation technique. The advantage of the technique used in the computation of ATC is that it has the ability to reduce the time consuming ac power flow computations. The cubic-spline interpolation technique traces the curves of voltage magnitude and power flow variations with respect to the increase of real power transfer. ATC is then determined at the point where the voltage or power flow limits intersect the curves. Prior to the ATC evaluation, contingency ranking and selection techniques are used to define the critical lines in a system that can adversely affect the transfer capability assessment. The effectiveness of the proposed method is verified by illustrating the ATC evaluation on a practical test system. ATC results obtained from the proposed cubic-spline interpolation technique prove that the method is satisfactorily accurate and it is faster than the ATC method using the recursive ac power flow computations.