7,533 research outputs found
Spherical Tuples of Hilbert Space Operators
We introduce and study a class of operator tuples in complex Hilbert spaces,
which we call spherical tuples. In particular, we characterize spherical
multi-shifts, and more generally, multiplication tuples on RKHS. We further use
these characterizations to describe various spectral parts including the Taylor
spectrum. We also find a criterion for the Schatten -class membership of
cross-commutators of spherical -shifts. We show, in particular, that
cross-commutators of non-compact spherical -shifts cannot belong to
for .
We specialize our results to some well-studied classes of multi-shifts. We
prove that the cross-commutators of a spherical joint -shift, which is a
-isometry or a -expansion, belongs to if and only if . We
further give an example of a spherical jointly hyponormal -shift, for which
the cross-commutators are compact but not in for any .Comment: a version close to final on
Stable Prehensile Pushing: In-Hand Manipulation with Alternating Sticking Contacts
This paper presents an approach to in-hand manipulation planning that
exploits the mechanics of alternating sticking contact. Particularly, we
consider the problem of manipulating a grasped object using external pushes for
which the pusher sticks to the object. Given the physical properties of the
object, frictional coefficients at contacts and a desired regrasp on the
object, we propose a sampling-based planning framework that builds a pushing
strategy concatenating different feasible stable pushes to achieve the desired
regrasp. An efficient dynamics formulation allows us to plan in-hand
manipulations 100-1000 times faster than our previous work which builds upon a
complementarity formulation. Experimental observations for the generated plans
show that the object precisely moves in the grasp as expected by the planner.
Video Summary -- youtu.be/qOTKRJMx6HoComment: IEEE International Conference on Robotics and Automation 201
Adaptive Information Visualization for Personalized Access to Educational Digital Libraries
Personalization is one of the emerging ways to increase the power of modern Digital Libraries. The Knowledge Sea II system presented in this paper explores social navigation support, an approach for providing personalized guidance within the open corpus of educational resources. Following the concepts of social navigation we have attempted to organize a personalized navigation support that is based on past learners’ interaction with the system. The study indicates that Knowledge Sea II became the students' primary tool for accessing the open corpus documents used in a programming course. The social navigation support implemented in this system was considered useful by students participating in the study of Knowledge Sea II. At the same time, some user comments indicated the need to provide more powerful navigational support, such as the ability to rank the usefulness of a page
TOWARDS DEMAND DRIVEN PUBLISHING: APPROCHES TO THE PRIORITISATION OF DIGITISATION OF NATURAL HISTORY COLLECTIONS DATA
Natural history collections represent a vast repository of biodiversity data of international significance. There is an imperative to capture the data through digitisation projects in order to expose the data to new and established users of biodiversity data. On the basis of review of current state of digitization of natural history collections, a demand driven approach is advocated through the use of metadata to promote and increase access to natural history collection data
- …