Asymptotic control theory for a system of linear oscillators

We present an asymptotic control theory for a system of an arbitrary number of linear oscillators under a common bounded control. We suggest a design method of a feedback control for this system. By using the DiPerna-Lions theory of singular ODEs, we prove that the suggested control law correctly defines the motion of the system. The obtained control is asymptotically optimal: the ratio of the motion time to zero under this control to the minimum one is close to 1 if the initial energy of the system is large. The results are partially based on a new perturbation theory of observable linear systems.Comment: 34 pages; published versio

Perturbation theory of observable linear systems

The present work is motivated by the asymptotic control theory for a system of linear oscillators: the problem is to design a common bounded scalar control for damping all oscillators in asymptotically minimal time. The motion of the system is described in terms of a canonical system similar to that of the Pontryagin maximum principle. We consider the evolution equation for adjoint variables as a perturbed observable linear system. Due to the perturbation, the unobservable part of the state trajectory cannot be recovered exactly. We estimate the recovering error via the $L_1$-norm of perturbation. This allows us to prove that the control makes the system approach the equilibrium state with a strictly positive speed.Comment: 7 pages; the subject of the present paper has grown out of study arXiv:1308.6090 (see Appendix V); published versio

ASSESSMENT OF STUDENTS’ MEDIA COMPETENCE: TEST RESULTS ANALYSI

Ascertaining levels of media competence (development in the field of media culture) of students is based on the classification of indicators developed by the author. In accordance with this classification, audience is invited to a basic blocks of questions and tasks. The gargets are: to detect the levels of motivational indicators of audience’s media competence (genre, thematic, psychological, therapeutic, emotional, cognitive, moral, intellectual, creative and aesthetic reasons which the audience contact with media texts); to identify the level of the user / contact rate (frequency of contacts with various kinds of media, user skills in relation to the media); to identify the level of cognitive / information index (knowledge of terminology, history and theory of media culture) of university students’ media competence

Russian Media Educators: Case Studies Portraits

This article is devoted to case studies of the media education works of some well knowns Russian media educators. The analysis of media educational work of the famous Russian media educators leads us to the conclusion that media education in Russia is developing, building on the synthesis of the aesthetic, socio-cultural, and practical concepts, with a focus on the development of media competence of the audience, mainly school and youth. The enthusiasts of media education, even devoid of substantial public support for its innovative projects, achieve significant and meaningful results

Stabilization of Hypersonic Boundary Layers by Porous Coatings

A second-mode stability analysis has been performed for a hypersonic boundary layer on a wall covered by a porous coating with equally spaced cylindrical blind microholes. Massive reduction of the second mode amplification is found to be due to the disturbance energy absorption by the porous layer. This stabilization effect was demonstrated by experiments recently conducted on a sharp cone in the T-5 high-enthalpy wind tunnel of the Graduate Aeronautical Laboratories of the California Institute of Technology. Their experimental confirmation of the theoretical predictions underscores the possibility that ultrasonically absorptive porous coatings may be exploited for passive laminar flow control on hypersonic vehicle surfaces

Loss-tolerant quantum enhanced metrology and state engineering via the reverse Hong-Ou-Mandel effect

Preparing highly entangled quantum states between remote parties is a major challenge for quantum communications [1-8]. Particularly promising in this context are the N00N states, which are entangled N-photon wavepackets delocalized between two different locations, providing measurement sensitivity limited only by the uncertainty principle [1, 10-15]. However, these states are notoriously vulnerable to losses, making it difficult both to share them between remote locations, and to recombine them to exploit interference effects. Here we address this challenge by utilizing the reverse version of the Hong-Ou-Mandel effect [16] to prepare a high-fidelity two-photon N00N state shared between two parties connected by a lossy optical channel. Furthermore, we demonstrate that the enhanced phase sensitivity can be directly exploited in the two distant locations, and we remotely prepare superpositions of coherent states, known as Schr\"odinger's cat states" [17, 18]