Multiattribute Decision Making Methodology in the Concept Design of Tankers and Bulk Carriers

An improved methodology for decision making for ship general design in concept design phase is presented. Multiattribute decision making method has been applied and executed by decision making shell DeMak developed at Faculty of Mechanical Engineering and Naval Architecture in Zagreb. Each attribute was defi ned through membership grade function based on fuzzy set theory. The consistent relative signifi cance of attributes is obtained as an eigenvector of subjective decision making matrix and used as a weighting factor. Inadequate information about confi guration of feasible designs´ subspace is overcome by sequential adaptive generation of design points in feasible region (via e.g. adaptive Monte Carlo method). The concept of nondominated designs was used for fi ltering effi cient (Pareto) solutions which are the only signifi cant ones from the designer point of view. Selection among effi cient solutions is performed by MADM approach, thus expressing designer´s heuristic preference regarding multiple attributes. As “preferred design”, the nondominated point having a minimal distance from the “utopia” or other target design in the subjective attribute space have to be selected. Method is presented for the basic design of Capesize bulk carrier and Handymax product tanker. Design procedure and mathematical models for basic design of tankers and bulk carriers has been taken over complementaty paper [B1]

Updating the Lambda modes of a nuclear power reactor

[EN] Starting from a steady state configuration of a nuclear power reactor some situations arise in which the reactor configuration is perturbed. The Lambda modes are eigenfunctions associated with a given configuration of the reactor, which have successfully been used to describe unstable events in BWRs. To compute several eigenvalues and its corresponding eigenfunctions for a nuclear reactor is quite expensive from the computational point of view. Krylov subspace methods are efficient methods to compute the dominant Lambda modes associated with a given configuration of the reactor, but if the Lambda modes have to be computed for different perturbed configurations of the reactor more efficient methods can be used. In this paper, different methods for the updating Lambda modes problem will be proposed and compared by computing the dominant Lambda modes of different configurations associated with a Boron injection transient in a typical BWR reactor. (C) 2010 Elsevier Ltd. All rights reserved.This work has been partially supported by the Spanish Ministerio de Educacion y Ciencia under projects ENE2008-02669 and MTM2007-64477-AR07, the Generalitat Valenciana under project ACOMP/2009/058, and the Universidad Politecnica de Valencia under project PAID-05-09-4285.González Pintor, S.; Ginestar Peiro, D.; Verdú Martín, GJ. (2011). Updating the Lambda modes of a nuclear power reactor. Mathematical and Computer Modelling. 54(7):1796-1801. https://doi.org/10.1016/j.mcm.2010.12.013S1796180154