A general framework for structure-preserving model reduction by Krylov subspace projection methods is developed. It not only matches as many moments as possible but also preserves substructures of importance in the coefficient matrices L,G,C, and B that define a dynamical system prescribed by the transfer function of the form H(s)=L∗(G+sC)−1B. Many existing structurepreserving model-order reduc...

In this article we study the MOR cryptosystem. We use the group of unitriangular matrices over a finite field as the non-abelian group in the MOR cryptosystem. We show that a cryptosystem similar to the ElGamal cryptosystem over finite fields can be built using the proposed groups and a set of automorphisms of these groups. We also show that the security of this proposed MOR cryptosystem is equ...

In the last years, pruning techniques based on partial order reduction have found increasing attention in the planning community. One recent result is that the expansion core method is a special case of the strong stubborn sets method proposed in model checking. However, it is still an open question if there exist efficiently computable strong stubborn sets with strictly higher pruning power th...

The super node algorithm performs model order reduction based on physical principles. Although the algorithm provides us with compact models, its stability and passivity have not thoroughly been studied yet. The loss of passivity is a serious problem because simulations of the reduced network may encounter artificial behavior which render the simulations useless. In this paper we explain why th...

This paper focuses on the model order reduction problem of second-order form models. The aim is to provide a reduction procedure which guarantees the preservation of the physical structural conditions of second-order form models. To solve this problem, a new approach has been developed to transform a second-order form model from a state-space realization which ensures the preservation of the st...

A general framework for structure-preserving model reductions by Krylov subspace projection methods is developed. It not only matches as many moments as possible but also preserves substructures of importance in the coefficient matrices L,G,C, and B that define a dynamical system prescribed by the transfer function of the form H(s) = L∗(G+sC)−1B. Many existing structure-preserving model-order r...

The paper cryptanalyses a new public key cryptosystem that has been recently proposed by Paeng, Ha, Kim, Chee and Park [5]. The scheme works on finite non-abelian groups. We focus on the group SL(2, ZZp)×θ ZZp which was discussed in [5] extensively.

In this paper we study the MOR cryptosystem with finite Chevalley groups. There are four infinite families of finite classical Chevalley groups. These are: special linear groups SL(d, q), orthogonal groups O(d, q) and symplectic groups Sp(d, q). The family O(d, q) splits to two different families of Chevalley groups depending on the parity of d. The MOR cryptosystem over SL(d, q) was studied by...

This paper describes the use of a quadratic manifold for the model order reduction of structural dynamics problems featuring geometric nonlinearities. The manifold is tangent to a subspace spanned by the most relevant vibration modes, and its curvature is provided by modal derivatives obtained by sensitivity analysis of the eigenvalue problem, or its static approximation, along the vibration mo...

In this paper we review two recently suggested projection techniques for model order reduction of bilinear systems. The first one is computationally more attractive, but so far it was assumed that this method does not yield a moment-matching approximation. Here we show that the reduced-order models computed by both of the two projection techniques match multimoments of the bilinear system. This...