Modal absorptions in laser-like heterostructures containing InAs self-assembled quantum dots (QDs) and InGaAs quantum well-dots (QWDs) have been studied. The evaluation of photoresponse as a function ...of waveguide length has allowed us to determine per-layer modal absorptions of 69 and 13 cm -1 for the ground state optical transitions of QWDs and QDs, respectively. The values of the modal absorption can be used as a measure of the maximal (saturated) modal gain. To compare quantum heterostructures with different dimensionality we have introduced the layer gain constant, a parameter characterizing the light transmittance through the absorbing or gaining layer. We have shown that the QWD layer gain constant significantly exceeds quantum well and quantum dot ones.
Fluorozirconate–phosphate glasses in the ZrF4–BaF2(SnF2)–NaPO3 and 53ZrF4–30BaF2–(17−x)NaPO3–xMF3 systems (M=Ga, In, Bi; 1≤x≤5) have been prepared and characterized by differential thermal analysis ...(DTA), 19F nuclear magnetic resonance (NMR), 19F and 31P magic-angle spinning (MAS) NMR, small-angle X-ray scattering (SAXS), and transmission electron microscopy (TEM). It was shown that glasses consisted of fluorozirconate and phosphate subsystems, which coexisted independently. The additives of metal trifluorides MF3 do not virtually affect thermal characteristics of fluorozirconate subsystem but decrease gradually the crystallization temperature (Tc2) of phosphate subsystem According to the SAXS and TEM data, the fluorozirconate–phosphate glasses have the globular structure with the particles size of 50–560Å. Mixed fluorozirconate–phosphate glasses can be considered as precursors for obtaining new functional materials.
•ZrF4–BaF2(SnF2)–NaPO3, 53ZrF4-30BaF2–(17−x)NaPO3–xMF3 glasses (1≤x≤5) were studied.•Behavior and properties of these glasses are similar to fluorozirconate glasses.•The fluorozirconate and phosphate subsystems in the glasses coexist independently.•The glass microstructure is globular with a particle diameter of 50–560Å.•These glasses can be used as precursors for the mixed optical nanoceramics.
The applicability of a KTA crystal-based laser system with optical parametric oscillators (OPO) generation to lidar sounding of the atmosphere in the spectral range 3–4 μm is studied in this work. A ...technique developed for lidar sounding of trace atmospheric gases (TAG) is based on differential absorption lidar (DIAL) method and differential optical absorption spectroscopy (DOAS). The DIAL-DOAS technique is tested to estimate its efficiency for lidar sounding of atmospheric trace gases. The numerical simulation performed shows that a KTA-based OPO laser is a promising source of radiation for remote DIAL-DOAS sounding of the TAGs under study along surface tropospheric paths. A possibility of using a PD38-03-PR photodiode for the DIAL gas analysis of the atmosphere is shown.
Siberian lidar station: instruments and results Matvienko, Gennadii G.; Balin, Yurii S.; Bobrovnikov, Sergey M. ...
EPJ Web of Conferences,
01/2018, Volume:
176
Journal Article, Conference Proceeding
Peer reviewed
Open access
The Siberian Lidar Station created at V.E. Zuev Institute of Atmospheric Optics and operating in Tomsk (56.5° N, 85.0° E) is a unique atmospheric observatory. It combines up-to-date instruments for ...remote laser and passive sounding for the study of aerosol and cloud fields, air temperature and humidity, and ozone and gaseous components of the ozone cycles. In addition to controlling a wide range of atmospheric parameters, the observatory allows simultaneous monitoring of the atmosphere throughout the valuable altitude range 0–75 km. In this paper, the instruments and results received at the Station are described.
The electrodynamic characteristics of a high-Q dielectric whispering gallery mode resonator in the form of a hemisphere positioned on an impedance plane were studied. The analysis of the anisotropic ...resonator was modeled using Maxwell equations and the impedance Leontovich boundary condition. The interaction coefficient A S j of the conductor and microwave field was determined using a frequency and field distribution of the j-type mode in the hemisphere resonator considering a perfect conducting plane. Results of the theoretical study and experimental measurements of the Teflon resonator frequency spectrum and Q factor are in good agreement. The results obtained are confirmed by calculations using Microwave Studio CST 2008. In the case of the sapphire hemispherical resonator with an impedance plane, comparison of the experimental and simulation results allows us to identify the H -type modes in the resonator and their electromagnetic field distribution. In such anisotropic hemisphere resonators, the quasi-TE modes are revealed. The modes are excited together with TE modes inherent to the isotropic resonator and they have an identical distribution of electromagnetic field.
Novel solution precursors for CeO2 buffer layers, based on mixed-ligand hydroxocomplexes of lanthanide acetates and nitrates with monoethanolamine (MEA) and diglyme, acting as both ligands and ...solvents, have been developed. The formation of mixed-ligand Ce(IV) complexes in both liquid and transparent gel precursors have been confirmed by electrospray ionization−mass spectroscopy (ESI-MS) and 1H nuclear magnetic resonance (NMR) spectroscopy. The features of thermal decomposition of gel precursor samples were studied using thermogravimetry (TG) and differential thermogravimetry (DTG) analyses in air and in argon. The advantages of the new precursors are the accessibility of high concentrations, stability, and excellent wetting behavior of Ni−5 at.% W substrates. Various elements can be easily incorporated into them as dopants, as was shown on an example of La3+. Epitaxial CeO2 and CeO2(La) films were deposited on Ni−W cube-textured tapes from developed solutions via the metal-organic chemical solution deposition (MOCSD) method. Incorporation of La3+ into the buffer layer leads to improvement in the oxide’s texture and the film’s surface.
INDUSTRIAL MECHATRONIC ELECTROPNEUMATIC DRIVES Yury V. ILYUKHIN; Alexander N. KHARCHENKO; Sergey A. ARFIKYAN
Vestnik Donskogo gosudarstvennogo tehničeskogo universiteta (Online),
08/2018, Volume:
10, Issue:
8
Journal Article
Peer reviewed
Open access
The construction concept, the structural features and the experimental results of dynamic behaviour of industrial electropneumatic servo drives built on the ground of the mechatronic approach are ...described. It is proved that such drives are of high precision and operation speed.
Noise reduction issues in the developed world receive an increasing attention, which is reflected in a great tightening of the noise level requirements. For the practical solution of this problem ...authors propose a new high-performance numerical modeling method of three-dimensional tonal noise acoustic field generated by the fan as a bladed machine. The method is based on solving a boundary value problem for Fourier transformed convective wave equation with complex variables in a Cartesian coordinate system in the arbitrary domain with impedance boundary conditions by finite volume method. The noise source is set in the form of sound power on the surface near the rotor that bounds the area of the vortex perturbations (pseudosound). Sound power is determined by acoustic-vortex method. There are shown examples of the method validation and application.
Analysis of dental radiographs is an important part of the diagnostic process in daily clinical practice. Interpretation by an expert includes teeth detection and numbering. In this project, a novel ...solution based on convolutional neural networks (CNNs) is proposed that performs this task automatically for panoramic radiographs.
A data set of 1352 randomly chosen panoramic radiographs of adults was used to train the system. The CNN-based architectures for both teeth detection and numbering tasks were analyzed. The teeth detection module processes the radiograph to define the boundaries of each tooth. It is based on the state-of-the-art Faster R-CNN architecture. The teeth numbering module classifies detected teeth images according to the FDI notation. It utilizes the classical VGG-16 CNN together with the heuristic algorithm to improve results according to the rules for spatial arrangement of teeth. A separate testing set of 222 images was used to evaluate the performance of the system and to compare it to the expert level.
For the teeth detection task, the system achieves the following performance metrics: a sensitivity of 0.9941 and a precision of 0.9945. For teeth numbering, its sensitivity is 0.9800 and specificity is 0.9994. Experts detect teeth with a sensitivity of 0.9980 and a precision of 0.9998. Their sensitivity for tooth numbering is 0.9893 and specificity is 0.9997. The detailed error analysis showed that the developed software system makes errors caused by similar factors as those for experts.
The performance of the proposed computer-aided diagnosis solution is comparable to the level of experts. Based on these findings, the method has the potential for practical application and further evaluation for automated dental radiograph analysis. Computer-aided teeth detection and numbering simplifies the process of filling out digital dental charts. Automation could help to save time and improve the completeness of electronic dental records.
Simulation of the water flow around a ship hull and a marine propeller operation are considered in this paper as popular problems of ship propulsion, which are frequently investigated through CFD ...approach now. CFD technologies are used for determination of ship hull resistance as well as the open water curves of the propeller according to usual methods of ship design. FlowVision CFD software is used for simulations based on solving RANS equations. The software was used together with supercomputer "HPC 2" of National Research Center "Kurchatov Institute". The original features of the numerical models and technologies, software algorithms and the supercomputer's hardware are submitted and discussed. There are the method of grid formation based on Cartesian initial grid and chimerical overlapping boundary layer grid, special versions of turbulence models, modified method of free surface simulation and many other things among them. Governing equations for water flow, which are integrated using an implicit numerical method, are given as well. The generated systems of linear equations are solved by an aggregative algebraic multigrid method. The scalability of this method on the supercomputer has been studied and analyzed.
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