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Full-Text Articles in Engineering
Subband Absolute Moment Block Truncation Coding, Kai-Kuang Ma, Sarah A. Rajala
Subband Absolute Moment Block Truncation Coding, Kai-Kuang Ma, Sarah A. Rajala
Sarah A. Rajala
In this paper, a new subband coding system called subband absolute moment block truncation coding (SAMBTC) is introduced to compress monochrome images and color images recorded in YIQ and L*u*v* uniform color spaces. The SAMBTC incorporates full‐band absolute moment block truncation coding (AMBTC) into subbands along with a new subband dynamic bit allocation algorithm which is derived from the Shannon rate‐distortion bound. Simulation results show that the proposed Shannon/bound‐based bit allocation algorithm outperforms the commonly used standard‐deviation‐based bit allocation scheme. Compared with ABMTC, SAMBTC achieves superior imaging without blocking artifacts at low bit rates
Low‐Frequency Perturbation Theory In Eddy‐Current Non‐Destructive Evaluation, Nicola Harfield, Y. Yoshida, John R. Bowler
Low‐Frequency Perturbation Theory In Eddy‐Current Non‐Destructive Evaluation, Nicola Harfield, Y. Yoshida, John R. Bowler
Nicola Bowler
A method is presented by which series solutions for the impedance change in an eddy‐current test probe due to closed cracks in a non‐magnetic, conducting half‐space can be derived at low frequency. The series solution is applicable for flaws whose dimensions are much smaller than the electromagnetic skin‐depth. The problem is formulated using an approach in which the flaw is represented by an equivalent distribution of current dipoles. The electric field scattered by the flaw is then written as an integral, over the flaw, of the product of the dipole density distribution and an appropriate Green’s function. Terms in the …