1,765,241 research outputs found
A super-Ohmic energy absorption in driven quantum chaotic systems
We consider energy absorption by driven chaotic systems of the symplectic
symmetry class. According to our analytical perturbative calculation, at the
initial stage of evolution the energy growth with time can be faster than
linear. This appears to be an analog of weak anti-localization in disordered
systems with spin-orbit interaction. Our analytical result is also confirmed by
numerical calculations for the symplectic quantum kicked rotor.Comment: 4 pages, 2 figure
Thermalisation by a boson bath in a pure state
We consider a quantum system weakly coupled to a large heat bath of harmonic
oscillators. It is well known that such a boson bath initially at thermal
equilibrium thermalises the system. We show that assuming a priori an
equilibrium state is not necessary to obtain the thermalisation of the system.
We determine the complete Schr\"odinger time evolution of the subsystem of
interest for an initial pure product state of the composite system consisting
of the considered system and the bath. We find that the system relaxes into
canonical equilibrium for almost all initial pure bath states of
macroscopically well-defined energy. The temperature of the system asymptotic
thermal state is determined by the energy of the initial bath state as the
corresponding microcanonical temperature. Moreover, the time evolution of the
system is identical to the one obtained assuming that the boson bath is
initially at thermal equilibrium with this temperature. A significant part of
our approach is applicable to other baths and we identify the bath features
which are requisite for the thermalisation studied
Coupling device
Releasable coupling device designed to receive and retain matching ends of electrical connector
Power coupling
Power coupling is the subject of a huge amount of literature and material
since for each particular RF structure it is necessary to design a coupler that
satisfies some requirements, and several approaches are in principle possible.
The choice of one coupler with respect to another depends on the particular RF
design expertise. Nevertheless some 'design criteria' can be adopted and the
scope of this paper is to give an overview of the basic concepts in power
coupler design and techniques. We illustrate both the cases of
normal-conducting and superconducting structures as well as the cases of
standing-wave and travelling-wave structures. Problems related to field
distortion induced by couplers, pulsed heating, and multipacting are also
addressed. Finally a couple of design techniques using electromagnetic codes
are illustrated. The paper brings together pictures, data, and information from
several works reported in the references and I would like to thank all the
authors of the papers.Comment: 23 pages, contribution to the CAS - CERN Accelerator School:
Specialised Course on RF for Accelerators; 8 - 17 Jun 2010, Ebeltoft, Denmar
Prosthesis coupling
A coupling for use in an apparatus for connecting a prosthesis to the bone of a stump of an amputated limb is described which permits a bio-compatible carbon sleeve forming a part of the prosthesis connector to float so as to prevent disturbing the skin seal around the carbon sleeve. The coupling includes a flexible member interposed between a socket that is inserted within an intermedullary cavity of the bone and the sleeve. A lock pin is carried by the prosthesis and has a stem portion which is adapted to be coaxially disposed and slideably within the tubular female socket for securing the prosthesis to the stump. The skin around the percutaneous carbon sleeve is able to move as a result of the flexing coupling so as to reduce stresses caused by changes in the stump shape and/or movement between the bone and the flesh portion of the stump
The Hagedorn temperature of AdS5/CFT4 at finite coupling via the Quantum Spectral Curve
Building on the recently established connection between the Hagedorn
temperature and integrability [Phys.Rev.Lett. 120 (2018) no.7, 071605], we show
how the Quantum Spectral Curve formalism can be used to calculate the Hagedorn
temperature of AdS5/CFT4 for any value of the 't Hooft coupling. We solve this
finite system of finite-difference equations perturbatively at weak coupling
and numerically at finite coupling. We confirm previous results at weak
coupling and obtain the previously unknown three-loop Hagedorn temperature. Our
finite-coupling results interpolate between weak and strong coupling and allow
us to extract the first perturbative order at strong coupling. Our results
indicate that the Hagedorn temperature for large 't Hooft coupling approaches
that of type IIB string theory in ten-dimensional Minkowski space.Comment: 7 page
Quick connect coupling
A coupling device has a transversely arranged, open-end groove in a flange attached to a pipe end. The groove in the flange receives a circumferentially arranged locking flange element on the other coupling member and permits alignment of the bores of the coupling members when the locking flange element is in the open end groove. Upon alignment of the bores of the coupling members, a trigger member is activated to automatically release a spring biased tubular member in one of the coupling members. The tubular member has a conical end which is displaced into the other coupling member to lock the coupling members to one another. A tensioning nut is threadedly movable on a coupling member so as to be moved into tightening engagement with the other coupling member
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