Concrete permeability is a major factor that affects durability and reliability of structures – bridges, tunnels, culvert pipes, etc. It is important to identify effective methods of protection of ...such structures against water penetration, for example by using a modifying substance. Samples of cement mortar composites were used for water absorption simulation. Bitumen emulsion was used as a modifying agent. According to the water absorption kinetics, the following parameters of the pore microstructure of the mortar composite were estimated: the index of mean size of open capillary pores, closed porosity, and the index of size uniformity. The research has shown that the addition of bitumen emulsion decreases the pore space and macrocapillaries (from 23.91% to 6.61%), water absorption (3 times), and the index of mean size of open capillary pores (from 0.69 to 0.3) of modified mortars.
Odpowiednio niska przepuszczalność betonu to jeden z głównych czynników zapewniających trwałość i niezawodność konstrukcji budowlanych – mostów, tuneli, przepustów itd. Istotne jest zidentyfikowanie skutecznych metod zabezpieczenia takich konstrukcji przed wnikaniem wody, na przykład za pomocą dodatków modyfikujących. Badania nasiąkliwości przeprowadzono na próbkach zaprawy cementowej zawierającej dodatek emulsji asfaltowej. Na podstawie kinetyki wnikania wody w próbki oszacowano następujące parametry uzyskanej mikrostruktury porów: wskaźnik średniej wielkości otwartych porów kapilarnych, porowatość zamkniętą oraz wskaźnik jednorodności wielkości otwartych porów kapilarnych. Wyniki wykazały, że dodatek emulsji asfaltowej zmniejszył objętość porów i makrokapilar (z 23,91% do 6,61%), nasiąkliwość (trzykrotnie) oraz wskaźnik średniej wielkości kapilar otwartych (z 0,69 do 0,3) zapraw poddanych modyfikacji dodatkiem.
Automated Osborn wave detection system featuring the sensitivity of 94.63% and classification accuracy of 94.58% for the notch and slur types of waves in the cardiac signal has been developed. The ...quasi-matched wavelet filtering method and the method of principal components were applied for extraction and formation of feature vectors representing the input data of classifier. The error feedforward neural network with topology of a multilayer perceptron was used as a classifier. Signal samplings built on information from the PhysioNet open database of medical signals were used for training, testing and validation of neural network. This study involved the use of 12-lead electrocardiograms of 60 healthy patients aged 17–87. These electrocardiograms formed the basis for creating a database of 14832 signals (9888 with Osborn wave signals of two types and 4944 signals without pathological findings). The proposed approach ensured the classification accuracy exceeding the accuracy of existing techniques.
TAIGA (Tunka Advanced Instrument for Gamma Astronomy) is designed for studying gamma rays and charged cosmic particles in the energy range of 10
13
–10
18
eV. The staff of the Joint Institute for ...Nuclear Research is now working on the design and fabrication of Cherenkov telescope elements (IACTs). The IACT field of view is ~10° × 10°, due to a Davis–Cotton optical layout with 34 mirrors 0.60 m in diameter, a focal length of 4.75 m, and 560 XP1911 PMT camera. The first IACT was commissioned in 2016 in the Tunka Valley. The second IАСТ is now being prepared for operation. The steps of PMT alignment and the results from its calibration are thoroughly described along with the fabrication of a mirror and its optical parameters. The technique for adjusting the mirror is presented as well. It replaces the conventional visual assessment of the image with pattern recognition software that is applied to a screen shot of the calibration source. This software ensures highly precise calculations of the mirror’s adjusting screws to obtain a correct image.
To substantiate the relationship between the quality of HBI and the material composition of pellets and the concentrate from which they were obtained, an array of data on the operation of the ...operating Hyl-3 metallization unit was used. The following are the main results of the work: (1) there is a pattern in the change in the quality of HBI and the performance of shaft furnaces, depending on the mineral composition of the original ore and concentrate, the effect of which is manifested even after granulation and heat treatment of pellets; (2) regularities of the influence of the material composition of the concentrate can be estimated numerically, and these digital models can become the basis for predictive control systems and equipment operation forecasting; (3) the direction of digitalization of pellets and HBI production is promising, associated with a comprehensive analysis of the operation of technological lines and consistent “characterization” of ore (by geochemical markers or mineral composition) based on equipment control models. The potential for improving the quality of HBI through the use of predictive models is estimated by the following values: by the degree of metallization—by 2% (abs.); by carbon content—by 0.1% (abs); for drum test +25 mm—by 1.7% (abs.).
Optical and electrical properties of MoSe2 monolayer transferred to graphene/SiC substrate are studied by scanning probe microscopy and photoluminescence spectroscopy. By Kelvin probe microscopy it ...was measured a work function of the MoSe2 monolayer (4.3 eV) and it was revealed the n-type of doping. With the increasing of MoSe2 layers quantity the work function also increases which leads to the reducing of the Schottky barrier height between the SPM probe and the layers. Monolayer graphene quenches photoluminescence of the MoSe2 monolayer while the bilayer graphene does not perturb the photoluminescence.
TAIGA array addresses gamma-ray astronomy at energies from a few TeV to several PeV as well as cosmic ray physics from 100 TeV to several EeV. A 1 km2 TAIGA setup will consist of 120 wide-angle ...detectors of the Cherenkov timing array TAIGA-HiSCORE and three imaging air Cherenkov telescopes with the field of view diameter of 9.6°. In this paper, first experimental results of the first operation stage are presented: signal detection from two gamma-ray sources, the Crab Nebula and Markarian 421, by the first IACT in stand-alone mode. The detected signal is shown to be in agreement with the Monte Carlo expectation. In future, gamma-ray signal will be detected by a larger number of TAIGA telescopes as well as the TAIGA-HiSCORE array, that is, in combined operation mode.
The paper deals with special class of diffusions with jumps. For the traditional class of such diffusions, the jumps occur at the moments corresponding to the moments of jumps of a Poisson process. ...The position at the moment of a jump can be arbitrary. A description of the traditional class of diffusions with jumps is well known. A natural generalization of this class and many other results are also given here. In the present paper, we consider diffusions, for which the position of diffusion in any moment of jump takes a finitely many values. Such moments, for example, are the first exit time from an interval, the moment inverse to the diffusion local time or the minimum of inverse local times. The results of interest are those that allow one to compute the distributions of various functionals of diffusion with jumps. For a diffusion, in particular for the Brownian motion, the results of M. Kac are of key importance for development of the theory of the distributions of integral functionals.
Main properties of holographic waveguide periscopic multiplexors of the exit pupil of optical systems of augmented reality displays are considered. Limitations in the operation of waveguide ...holograms, compensation of chromatic aberrations in periscopic schemes, and influence of waveguide defects on the operation of augmented reality displays constructed based on waveguide holograms are analyzed.
A problem of convective cooling of both freshwater and saltwater lake is formulated. A transient one-dimensional turbulent model with variable layer depth is proposed to describe the process of ...freezing. The dependence of layer depth on time is determined by a universal equation describing the propagation of Deardorff convective layer. A combination of the main form of equations of Kolmogorov–Obukhov theory and available experimental data is shown to allow the construction of a universal profile of turbulent exchange coefficient, depending on the height.
An ensemble of cold thermals in a convective layer of a fresh or salt water body is considered. The probability distribution density of the vertical velocities of thermals is assumed to satisfy the
K
...-form of Fokker−Planck equation. The
K
-form of the Fokker−Planck equation is shown to have a steady-state solution in the form of a generalized Maxwell distribution. Natural and numerical experiments were carried out to demonstrate the existence of such distribution. Lyapunov functional in the form of Kullback relationship was used to establish the nonlinear instability of this distribution with respect to small perturbations in the Hilbert space norm.
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