This article provides a comparison of a three methods that can be used for calculating effective coverage of image quality assessment database. The aim of this metric is to show how well the database is filled with variety of images. For each image in the database the Spatial Information (SI) and Colorfulness (CF) metric is calculated. The area of convex hull containing all the points on SI x CF plane is indication of total coverage of the database, but it does not show how efficiently this area is utilized. For this purpose an effective coverage was introduced. An analysis is performed for 16 databases - 13 publicaly available and 3 artificial created for the purpose of showing advantages of the effective coverage.
The method of calculations of a thick plate on the two-parameter layered foundation by the finiteelement method is presented. The numerical model allows to add a few (number of) foundationlayers. The expressions for the element stiffness matrices of the foundation are based on 18-nodezero-thickness interface elements. For modelling of thick plates the 9-node Mindlin element of theLagrange family is used. The formulation of the problem takes into account the shear deformation ofthe plate and unilateral contact conditions between plate and foundation. The tensionless characterof the foundation is achieved by removing from the global stiffness matrix the appropriate partof foundation stiffness attached to the node being in the separation stage. The advantages of theproposed algorithm are illustrated by numerical examples.
A numerical analysis of the initially clamped bolt joint subject to the working pressure is presented in the paper. Special, hexahedral 21- and 28-node isoparametric finite elements have been employed to model the contact zone. In this model, one takes into account loading due to the working pressure in the gap between the gasket and the flange arising as an effect of the progressing joint opening, what has not been considered in recent papers. Nonlinear stiffness characteristics of the bolt and the flange with the gasket are developed. Working pressure corresponding to the critical bolt force resulting in the joint leakage (complete opening between the gasket and the flange) is determined. FE computational results are compared with the available experimental results. The numerical results are presented using the authors' own graphical postprocessor.