It is shown that the result of Tso-Wu on the elliptical shape of the numerical range of quadratic operators holds also for the C*-algebra numerical range.

For any n×n matrix A , we use the joint higher rank numerical range, Λk(A, . . . ,Am) , to define the higher rank numerical hull of A . We characterize the higher rank numerical hulls of Hermitian matrices. Also, the higher rank numerical hulls of unitary matrices are studied. Mathematics subject classification (2010): 15A60,81P68.

Abstract. Let T1, . . . , Tn be bounded linear operators on a complex Hilbert space H. Then there are compact operators K1, . . . , Kn ∈ B(H) such that the closure of the joint numerical range of the n-tuple (T1−K1, . . . , Tn−Kn) equals to the joint essential numerical range of (T1, . . . , Tn). This generalizes the corresponding result for n = 1. We also show that if S ∈ B(H) and n ∈ N then t...

we give further results for perron-frobenius theory on the numericalrange of real matrices and some other results generalized from nonnegative matricesto real matrices. we indicate two techniques for establishing the main theorem ofperron and frobenius on the numerical range. in the rst method, we use acorresponding version of wielandt's lemma. the second technique involves graphtheory.

normal range of joint motion is an important factor in joint examination in clinical practice which is related to factors such as age, sex and geographic region. there is no data in the literature on the range of joint motions in healthy iranian adults. we studied joint motions in 100 healthy volunteer subjects, 49 men and 51 women, from 19 and 58 years of age. the joint mobility was examined i...

Although segmental tunnel linings are often used for seismic areas, the influence of segment joints on the segmental lining behavior under seismic loading has not been thoroughly considered in the literature. This paper presents the results of a numerical study investigating the effects of the rotational, axial, and radial joint stiffness of the longitudinal joints on the structural force...

In this paper, the behavior of the pseudopolynomial numerical hull of a square complex matrix with respect to structured perturbations and its radius is investigated.