A study of European hake Merluccius merluccius gill net selectivity was undertaken off the Algarve (Southern Portugal), between 1999 and 2001. Four nominal mesh sizes (70, 80, 90 and 100 mm) were used in fishing trials and the ‘share each length class catch total’ (SELECT) method was used to fit gill net selectivity curves. Hake were caught in the same size range by all mesh sizes, between 17 a...

This paper describes a new technology of mesh size control using a background overlay grid size function. A background overlay grid is generated first according to the defined size functions and then is used as the base grid for determining the mesh size at each point during the meshing process. The definitions, classifications, implementations and control algorithms of three types of size func...

This paper presents the mesh selectivity of a net pot for white-spotted conger eel Conger myriaster. A cover-net fishing experiment was carried out in October 1995 and 1996, using five mesh openings; 11.6, 13.6, 15.5, 18.1, and 21.0 mm with a cover-net of 10.8 mm mesh opening. Each mesh-size net pot had a slightly different mesh selectivity curve in terms of R(=G/P), girth ratio G to mesh perim...

The reconngurable mesh model (RN-mesh) for parallel computations exhibits some \strong" results of algorithms involving a constant number of broadcasting steps. Naturally, one can ask whether or not these constants are tight. Consider an nn directed reconngurable mesh (DRN-mesh) that computes a function f(n) in a constant number of steps T (directed indicates that the edges of the mesh are dire...

It is well known that the variations of the element size have to be controlled in order to generate a high-quality mesh. Hence, several techniques have been developed to limit the gradient of the element size. However, the obtained discretizations do not always reproduce the prescribed size function. This is of the major importance for quadrilateral meshes, since they are much more constrained ...

This paper propose and analyze the two-level stabilized finite element method for the stationary Navier-Stokes equations based on Newon iteration. This algorithm involves solving one small, nonlinear coarse mesh with mesh size H and two linear problems on the fine mesh with mesh size h. Based on local Gauss integration and the quadratic equal-order triangular element ,the two-level stabilized m...

Abstract—This paper reports an experimental investigation of the energy spectrum of turbulent velocity fields at low Reynolds numbers (Rλ) in grid turbulence. Hot wire measurements are carried out in grid turbulence with subjected to a 1.36:1 contraction of the wind tunnel. Three different grids are used: (i) large square perforated grid (mesh size 43.75 mm), (ii) small square perforated grid (...

Diamond-mesh codends are the most commonly used in demersal trawls. However, mesh geometry tends to vary these during fishing, which leads a less well-defined size selection process. This leaves one questioning rationality of regulating exploitation patterns based on when and (or) variation between hauls is highly variable. While it has been speculated theoretically investigated how much variab...