13 research outputs found
Zonal flow generation and its feedback on turbulence production in drift wave turbulence
Plasma turbulence described by the Hasegawa-Wakatani equations has been
simulated numerically for different models and values of the adiabaticity
parameter C. It is found that for low values of C turbulence remains isotropic,
zonal flows are not generated and there is no suppression of the meridional
drift waves and of the particle transport. For high values of C, turbulence
evolves toward highly anisotropic states with a dominant contribution of the
zonal sector to the kinetic energy. This anisotropic flow leads to a decrease
of a turbulence production in the meridional sector and limits the particle
transport across the mean isopycnal surfaces. This behavior allows to consider
the Hasegawa-Wakatani equations a minimal PDE model which contains the
drift-wave/zonal-flow feedback loop prototypical of the LH transition in plasma
devices.Comment: 14 pages, 7 figure
Temperature fluctuations induced by frictional heating in isotropic turbulence
La dynamique et l'évolution des fluctuations de température induites par la dissipation visqueuse dans une turbulence isotrope sont étudiées utilisant des Simulations Numériques Directes. Les résultats de ces simulations sont en désaccord avec les prédictions de deux études théoriques récentes. Les résultats sont expliqués par des arguments phénomenologiques
Local quenches in fracton field theory: non-causal dynamics and fractal excitation patterns
We study the out-of-equilibrium dynamics induced by a local perturbation in
fracton field theory. For the and -symmetric
free fractonic theories, we compute the time dynamics of several observables
such as the two-point Green function, condensate,
energy density, and the dipole momentum. The time-dependent considerations
highlight that the free fractonic theory breaks causality and exhibits
instantaneous signal propagation, even if an additional relativistic term is
included to enforce a speed limit in the system. For the theory in finite
volume, we show that the fracton wave front acquires fractal shape with
non-trivial Hausdorff dimension, and argue that this phenomenon cannot be
explained by a simple self-interference effect.Comment: v1: 25 pages, 7 figures; v2: 25 pages, 7 figures, references added,
minor correction
Biorealistic Response in Optoelectrically-Driven Flexible Halide-Perovskite Single-Crystal Memristors
The transition to smart wearable and flexible optoelectronic devices
communicating with each other and performing neuromorphic computing at the edge
is a big goal in next-generation optoelectronics. These devices should perform
their regular tasks supported by energy-efficient in-memory calculations. Here,
we study the response of the CsPbBr halide-perovskite single crystal
fabricated on the flexible polymer substrate and integrated with the
single-walled carbon nanotube thin film electrodes in a lateral geometry. We
show both photodetection functions combined with the synaptic functionality in
our device under the application of hybrid optoelectrical stimuli. Furthermore,
we demonstrate that our device exhibits frequency-dependent bidirectional
modification of synaptic weight with a sliding threshold similar to
biologically plausible Bienenstock-Cooper-Munro learning. The demonstrated
optoelectronic synaptic behavior in halide-perovskite single-crystals opens the
opportunity for the development of hybrid organic-inorganic artificial visual
systems
Photogrammetry: from field recording to museum presentation (Timiryazevo burial site, Western Siberia)
A 3D-recording project was introduced into practice in 2014 by Tomsk State University during investigation of Timiryazevo burial site (5th–10th centuries AD). During the excavation, three-dimensional models of the whole archaeological site were made at each stage, as well as individual records of all artifacts. 3D recording was conducted by SFM technology. The data obtained was used for research and in work on the exhibition project ‖Secrets of Timiryazevo Burial Site: The Circle of Life and Death in Siberian Shamanism‖. The exposition centers on unveiling the meaning of the rite of burying lookalike dolls of the deceased, which was practiced by many indigenous peoples of Siberia. The exposition is designed to enable the visitor to pass through the whole cycle of knowledge extraction together with archaeologists, the ―detectives of the past‖: from a bunch of strange miniscule objects found in the sand to reconstruction of the whole sophisticated rite of the ―ultimate funeral‖ including the burial of the deceased’s lookalike doll. The tools used to develop the topic included a stereoscopic video created with Autodesk 3D Studio MAX 2014 and displayed in the exhibition. Stereoscopic videos displayed by specialized museum equipment create a total participation effect, enabling any visitor to watch excavations step by step, in all their detail and from all perspectives
Geology, Petrology, and Mineralogy of Hornfels-like Rocks (Beerbachite) in the Early Paleozoic Olkhon Collisional Orogen (West Baikal Area, Russia)
Geological, mineralogical, and petrological observations are reported for hornfels-like fine-grained granular mafic rocks in the Early Paleozoic Olkhon collisional orogen (West Baikal area, Russia). The rocks are composed of orthopyroxene, clinopyroxene, amphibole, plagioclase, and ilmenite; some samples also contain olivine, phlogopite, spinel, and titanomagnetite (Opx+Cpx+Amp+Pl+Ilm±Ol±Bt±Spl±Ti-Mag). There are three occurrences of these rocks in the area: a 500 m × 1000 m field in the Shirokaya Valley, another occurrence within the Tazheran Massif (a complex of igneous and metamorphic rocks), and dismembered dikes on the southern margin of the Birkhin gabbro intrusion. The Shirokaya field is located between two 500 Ma intrusions of the Birkhin gabbro; the Tazheran occurrence coexists with syenite, including nepheline syenite, subalkaline gabbro, and marble protrusions; and the dismembered dikes coexist with carbonates and display progressive alteration of dolerite through typical granular varieties. The dikes associated with granite and marble veins mark a part of a large arc-shaped shear zone that traverses the whole intrusive body produced by rotation of a rigid gabbro block during the peak of tectonic deformation at 470–460 Ma. All three occurrences of the hornfels-like rocks lack any evident source of heat that would be responsible for the thermal alteration of the igneous protolith. We hypothesize that the precursor, subvolcanic dolerite, may have undergone autometamorphism maintained by self-generated heat. Mafic magma intruded during high-rate strike–slip faulting, which caused rapid recrystallization of magmatic minerals and produced the observed metamorphic structures. Proceeding from the controversy in the formation mechanisms, with a heat source required for hornfels but lacking from the sampled occurrences of hornfels-like rocks, we suggest identifying the latter as beerbachite, though the term has mostly fallen into disuse. The reason is that the Olkhon rocks we study have a mineralogy, structure, and texture that are perfectly identical to those of beerbachites described in publications from the first half of the 20th century
Photoinduced Transition from Quasi-Two-Dimensional Ruddlesden–Popper to Three-Dimensional Halide Perovskites for the Optical Writing of Multicolor and Light-Erasable Images
Optical
data storage, information encryption, and security labeling
technologies require materials that exhibit local, pronounced, and
diverse modifications of their structure-dependent optical properties
under external excitation. Herein, we propose and develop a novel
platform relying on lead halide Ruddlesden–Popper phases that
undergo a light-induced transition toward bulk perovskite and employ
this phenomenon for the direct optical writing of multicolor patterns.
This transition causes the weakening of quantum confinement and hence
a reduction in the band gap. To extend the color gamut of photoluminescence,
we use mixed-halide compositions that exhibit photoinduced halide
segregation. The emission of the films can be tuned across the range
of 450–600 nm. Laser irradiation provides high-resolution direct
writing, whereas continuous-wave ultraviolet exposure is suitable
for recording on larger scales. The luminescent images created on
such films can be erased during the visualization process. This makes
the proposed writing/erasing platform suitable for the manufacturing
of optical data storage devices and light-erasable security labels
Photoinduced Transition from Quasi-Two-Dimensional Ruddlesden–Popper to Three-Dimensional Halide Perovskites for the Optical Writing of Multicolor and Light-Erasable Images
Optical
data storage, information encryption, and security labeling
technologies require materials that exhibit local, pronounced, and
diverse modifications of their structure-dependent optical properties
under external excitation. Herein, we propose and develop a novel
platform relying on lead halide Ruddlesden–Popper phases that
undergo a light-induced transition toward bulk perovskite and employ
this phenomenon for the direct optical writing of multicolor patterns.
This transition causes the weakening of quantum confinement and hence
a reduction in the band gap. To extend the color gamut of photoluminescence,
we use mixed-halide compositions that exhibit photoinduced halide
segregation. The emission of the films can be tuned across the range
of 450–600 nm. Laser irradiation provides high-resolution direct
writing, whereas continuous-wave ultraviolet exposure is suitable
for recording on larger scales. The luminescent images created on
such films can be erased during the visualization process. This makes
the proposed writing/erasing platform suitable for the manufacturing
of optical data storage devices and light-erasable security labels