1,478 research outputs found
On Boussinesq-type models for long longitudinal waves in elastic rods
In this paper we revisit the derivations of model equations describing long
nonlinear longitudinal bulk strain waves in elastic rods within the scope of
the Murnaghan model in order to derive a Boussinesq-type model, and extend
these derivations to include axially symmetric loading on the lateral boundary
surface, and longitudinal pre-stretch. We systematically derive two forced
Boussinesq-type models from the full equations of motion and non-zero surface
boundary conditions, utilising the presence of two small parameters
characterising the smallness of the wave amplitude and the long wavelength
compared to the radius of the waveguide. We compare the basic dynamical
properties of both models (linear dispersion curves and solitary wave
solutions). We also briefly describe the laboratory experiments on generation
of bulk strain solitary waves in the Ioffe Institute, and suggest that this
generation process can be modelled using the derived equations.Comment: 19 pages, 5 figures, submitted to the Special Issue of Wave Motion,
"Nonlinear Waves in Solids", in Memory of Professor Alexander M. Samsono
Chemically peculiar stars: rotation, magnetic fields, evolution
В рамках данной работы проводится изучение наблюдаемых параметров химически пекулярных звезд, таких как скорости и периоды вращения, характеристики магнитных полей и фундаментальные параметры атмосферы, что должно позволить проследить эволюцию магнитных полей подобных объектов на временах их жизни на ГП.The aim of this work is to study observable properties of chemically peculiar stars, such as rotational properties, magnetic field strength and topology as well as fundamental parameters of their atmospheres which allow us to estimate evolutionary status of these objects. We aim to trace the evolution of magnetic fields in magnetic chemically peculiar stars in their lifetime on the MS
The Role of Nanoanalytics in the Development of Organic-Inorganic Nanohybrids—Seeing Nanomaterials as They Are
The functional properties of organic-inorganic (O-I) hybrids can be easily tuned by combining system components and parameters, making this class of novel nanomaterials a crucial element in various application fields. Unfortunately, the manufacturing of organic-inorganic nanohybrids still suffers from mechanical instability and insufficient synthesis reproducibility. The control of the composition and structure of nanosurfaces themselves is a specific analytical challenge and plays an important role in the future reproducibility of hybrid nanomaterials surface properties and response. Therefore, appropriate and sufficient analytical methodologies and technical guidance for control of their synthesis, characterization and standardization of the final product quality at the nanoscale level should be established. In this review, we summarize and compare the analytical merit of the modern analytical methods, viz. Fourier transform infrared spectroscopy (FTIR), RAMAN spectroscopy, surface plasmon resonance (SPR) and several mass spectrometry (MS)-based techniques, that is, inductively coupled plasma mass spectrometry (ICP-MS), single particle ICP-MS (sp-ICP-MS), laser ablation coupled ICP-MS (LA-ICP-MS), time-of-flight secondary ion mass spectrometry (TOF-SIMS), liquid chromatography mass spectrometry (LC-MS) utilized for characterization of O-I nanohybrids. Special attention is given to laser desorption ionization mass spectrometry (LDI-MS) as a reliable nanoanalytical platform for characterization of O-I hybrid nanomaterials, their quality, design verification and validation
Optical and electronic properties of low-density InAs/InP quantum dot-like structures devoted to single-photon emitters at telecom wavelengths
Due to their band-structure and optical properties, InAs/InP quantum dots
(QDs) constitute a promising system for single-photon generation at third
telecom window of silica fibers and for applications in quantum communication
networks. However, obtaining the necessary low in-plane density of emitters
remains a challenge. Such structures are also still less explored than their
InAs/GaAs counterparts regarding optical properties of confined carriers. Here,
we report on the growth via metal-organic vapor phase epitaxy and investigation
of low-density InAs/InP QD-like structures, emitting in the range of 1.2-1.7
m, which includes the S, C, and L bands of the third optical window. We
observe multiple photoluminescence (PL) peaks originating from flat QDs with
height of small integer numbers of material monolayers. Temperature-dependent
PL reveals redistribution of carriers between families of QDs. Via
time-resolved PL, we obtain radiative lifetimes nearly independent of emission
energy in contrast to previous reports on InAs/InP QDs, which we attribute to
strongly height-dependent electron-hole correlations. Additionally, we observe
neutral and charged exciton emission from spatially isolated emitters. Using
the 8-band kp model and configuration-interaction method, we
successfully reproduce energies of emission lines, the dispersion of exciton
lifetimes, carrier activation energies, as well as the biexciton binding
energy, which allows for a detailed and comprehensive analysis of the
underlying physics.Comment: 13 pages, 9 figure
- …