Recently the Jacobi-Davidson subspace iteration method has been introduced as a new powerful technique for solving a variety of eigenproblems. In this paper we will further exploit this method and enhance it with several techniques so that practical and accurate algorithms are obtained. We will present two algorithms, JDQZ for the generalized eigenproblem, and JDQR for the standard eigenproblem...

The Chebyshev tau method is examined in detail for a variety of eigenvalue problems arising in hydrodynamic stability studies, particularly those of Orr-Sommerfeld type. We concentrate on determining the whole of the top end of the spectrum in parameter ranges beyond those often explored. The method employing a Chebyshev representation of the fourth derivative operator, D 4, is compared with th...

Abstract. Zero-sum problems in abelian groups and covers of the integers by residue classes, are two different active topics initiated by P. Erdős more than 40 years ago and investigated by many researchers separately since then. In an earlier announcement [Electron. Res. Announc. Amer. Math. Soc. 9(2003), 51-60], the author claimed some surprising connections among these seemingly unrelated fa...

Correlations between 276 orthogonal electrocardiographic measurements and constitutional variables were made in 450 normal women, aged 18 to 90 years. Advancing age led to decreases in amplitudes, left QRS axis shift, rightward and superior displacement of the ST segment, and anterior shift of the T wave. QZ was absent in 1% of normal women over age 40. In the oldest subjects, Ry amplitude was ...

We discuss in detail the use of the structure function F,(x, Qs) of deep-inelastic neutrino scattering for testing quantum chromodynamics. QCD is entirely consistent with all data. However, we show that higher-twist (order 1/Q2) contributions, which are commonly neglected, can have a dramatic impact on interpretation of this result. At present the data are not accurate enough to determine the m...

Polarized neutron reflectivity and scanning electron microscopy with polarization analysis are combined to determine the magnetic structure of Co(6 nm)/Cu(6 nm) multilayers. These data resolve a controversy regarding the low-field state of giant-magnetoresistive (GMR) multilayers with weak coupling. As-prepared samples show a strong antiparallel correlation of in-plane ferromagnetic Co domains ...

.Mmtract. In thL~ paper the first infinite series of translation nets with nonabelian translation groups and a large number of parallel classes are constructed. For that purpose we investigate partial congruence partitions (PCPs) with at least one normal component. Two series correspond to partial congruence partitions containing one normal elementary abelian component. The construction results...

The observatton of a new type of perverse behavior of votmg rules-Brams and Ftshburn’s “no-show paradox”--led Mouhn to Introduce the Parttctpatton Axtom (PA) It requires that an elector’s failure to vote should never result m the election of a candtdate whom he/she prefers to the one elected tf he/she votes sincerely The present paper examines PA in the context of Condorcet-type conditions For ...

In this paper, a strong version of Wald’s Axiom of excess demand functions Z : P ⊂ IR >0 → IR n is introduced, namely “there exists σ > 0 such that p, q ∈ P, qZ(p) − δ ≤ 0, |δ| < σ, and Z(q) 6= Z(p) imply pZ(q) + δ > 0”. We show that Z satisfies the strong version of Wald’s Axiom iff −Z is a s-quasimonotone function introduced in An (2006). Consequently, an excess demand function Z satisfies th...

Numerically reliable algorithms to compute the periodic non-negative definite stabilizing solutions of the periodic differential Riccati equation (PRDE) and discrete-time periodic Riccati equation (DPRE) are proposed. For the numerical solution of PRDEs, a new multiple shooting-type algorithm is developed to compute the periodic solutions in an arbitrary number of time moments within one period...