Shape description and matching using integral invariants on eccentricity transformed images

Matching occluded and noisy shapes is a problem frequently encountered in medical image analysis and more generally in computer vision. To keep track of changes inside the breast, for example, it is important for a computer aided detection system to establish correspondences between regions of interest. Shape transformations, computed both with integral invariants (II) and with geodesic distance, yield signatures that are invariant to isometric deformations, such as bending and articulations. Integral invariants describe the boundaries of planar shapes. However, they provide no information about where a particular feature lies on the boundary with regard to the overall shape structure. Conversely, eccentricity transforms (Ecc) can match shapes by signatures of geodesic distance histograms based on information from inside the shape; but they ignore the boundary information. We describe a method that combines the boundary signature of a shape obtained from II and structural information from the Ecc to yield results that improve on them separately

On the beneficial effect of noise in vertex localization

A theoretical and experimental analysis related to the effect of noise in the task of vertex identication in unknown shapes is presented. Shapes are seen as real functions of their closed boundary. An alternative global perspective of curvature is examined providing insight into the process of noise- enabled vertex localization. The analysis reveals that noise facilitates in the localization of certain vertices. The concept of noising is thus considered and a relevant global method for localizing Global Vertices is investigated in relation to local methods under the presence of increasing noise. Theoretical analysis reveals that induced noise can indeed help localizing certain vertices if combined with global descriptors. Experiments with noise and a comparison to localized methods validate the theoretical results

A Taguchi approach for optimization of design parameters in a tube with coiled wire inserts

This study presents the determination of the optimum values of the design parameters in a tube with equilateral triangular cross-sectioned coiled wire inserts. The effects of the design parameters such as the ratio of the distance between the coiled wire and test tube wall to tube diameter (s/D), pitch ratio (P/D), ratio of the side length of equilateral triangle to tube diameter (a/D) and Reynolds number (Re) on heat transfer and pressure drop were investigated by using Taguchi method. The Nusselt number and friction factor were considered as performance parameters. An L9(34) orthogonal array was chosen as experimental plan. The goal of this study is to reach maximum heat transfer (i.e. Nusselt number) and minimum pressure drop (i.e. friction factor). First of all, each goal was optimized, separately. Then, all the goals were optimized together, considering the priority of the goals. Contribution ratios for each parameter on the heat transfer and pressure drop were determined. Consequently, the optimum results were found to be s/D = 0.0357, P/D = 1, a/D = 0.0714 and Re = 19800. © 2011 Elsevier Ltd. All rights reserved

Forced convective two phase flow analysis in a circular tube equipped with twisted tapes

In forced convection boiling systems, it is important to know the dynamic behavior for understanding and predicting the local and global stability of the system. Besides this, the instability phenomenon in the industrial processes in which two phase flow takes part becomes more of an issue. So, the mechanisms of instabilities and the ways of decreasing the stabilities are of interest of the researchers for a long time. In this study, the effects of pitch ratio, inlet temperature and the mass flow rate on two phase flow instabilities in a horizontal circular tube are investigated. The experiments are conducted under constant system pressure, and a constant heat input of 24 kW is applied to the outer surface of the circular test pipe having constant exit restriction. The results of two different pitch ratios are also compared with the smooth tube. For all investigated cases, the results are evaluated in terms of pressure drop type and density wave type oscillations. The time dependent measurements of top wall temperature, bottom wall temperature, inlet pressure and mass flow rate variations are also presented. The boundaries of the oscillations are found for both twisted tape and smooth channel. It is found that the unstable region of the flow extends while the distance between boundaries increases. It is observed that the system is more stable in the case of the lowest pitch ratio, and the increase of the pitch ratio causes system to be less stable. By the decrease of the inlet temperature, the single phase liquid region extends in the test tube and thus the system becomes more stable. © Sila Science

The prediction of heat transfer and fluid characteristics for equilateral triangular bodies in tandem arrangement by artificial neural networks

The objective of this study is to investigate the effect of the spacing between equilateral dual triangular bodies symmetrically placed into the channel axis under steady state conditions on heat transfer and fluid characteristics by using artificial neural networks (ANN). The Back Propagation (BP) training algorithm was applied to train the model. The successful application proved that ANN model can be used for predicting the Nusselt number and skin friction coefficient as a convenient and effective method. The distribution of local Nusselt number, skin friction coefficient along the channel wall and overall enhancement ratio of all investigated cases are presented