A robust algorithm (solver) for testing the single-phase stability of a multicomponent fluid under isochoric-isobaric conditions is developed. The approach is based on the quasi-Newton minimization ...of Helmholtz free energy. The solver does not need explicit Hessian calculation when used with properly scaled variables. The solver is not tied to a specific equation of state and is applicable when the derivatives are calculated using automatic differentiation. The generation of initial estimates only needs an auxiliary cubic equation of state. We analyze the robustness and performance of the solver and present calculations of the phase boundary for a number of mixtures using the cubic equation of state and the equation of state from the family of the statistical association fluid theory (SAFT).
The introduction of modern technologies in the learning process at school is an important task, both for the education system as a whole and for an individual teacher. The ability to work with new ...teaching aids allows the teacher to interest students in their subject. One of these tools is virtual and mixed reality headsets. The emphasis is on mixed reality, although the two are often closely related. The article provides a brief overview of works devoted to the use of mixed reality in teaching physics, a study of the readiness of students of a pedagogical university to use this technology in their future professional activities is carried out. The questionnaire for expert assessment of mixed reality developments has been modified, and a survey of experts in this field has been conducted. The results of the research may be of interest to teachers of various specialties, senior students and graduate students in the field of physics teaching methods.
The load-bearing floor is a box-shaped structure consisting of monolithic floor slabs cohesive with all walls and partitions located between them 1. The load of the bearing floor is transmitted only ...to the exterior walls. Thereby, the spaces within the outer walls located under the bearing floor and above it don't require any intermediate support. The effectiveness of the load-bearing floor construction implementation is the ability to obtain freedom while making planning decisions, re-planning in the process of the operation and reducing the consumption of structural materials for creation of the building carcass compared to the existing traditional structures 2. In 3 authors describe the technology of construction of the bearing floor and present the results of computational studies of the stress state of its elements in their different design. In this article we discuss the planning and design features of the load-bearing floor in steel-reinforced concrete structures of low-rise buildings.
Experimental evaluation of operational properties of the transport equipment allows to determine its technical level in real operational conditions. The test results can lay ground for developing ...initial data to design future equipment of this class. Results of the tests conducted to determine speed and braking properties of the Russian-made utility terrain vehicles (UTV), models RM 650-2, RM 800 (by SC Russkaya Mekhanika), Stels 800 Guepard (by Group of Companies Velomotors), as well as foreign-made UTV, models Yamaha Grizzly, BRP Outlander Max XT, BRP Outlander 6×6, Polaris Sportsman 1000, Polaris Ranger EV4x4 are described in the article.
We have determined the thermal characteristics and optical properties of the sulfide and oxysulfide phases in the Nd2S3 - Nd2O3 system.
A congruent melting peak at temperature 1801 ± 4.9 °C with ...ΔH = 65.2 ± 6.7 kJ/mol was detected for the Nd2S3 compound by the DSC method. The characteristics of the α-Nd2S3 → γ-Nd2S3 polymorphic transition are t = 1183 ± 1.8°С, and ΔH = 7.5 ± 0.3 kJ/mol. The γ-Nd2S3 phase obtained upon cooling during annealing at 800 °C is retained for up to 30 h, and then the γ-Nd2S3 → α-Nd2S3 transition occurs within 20 h. The microhardness of the phases is: α-Nd2S3 H = 451 ± 4 HV; γ-Nd2S3 H = 531 ± 4 HV.
It was found by the TG method that the Nd10S14O phase thermally dissociates at temperatures above 1400 °C. The mass loss is 0.5 mass % at 1580 °C and 1.0 mass % at 1620 °C, but the samples remain single-phase ones after cooling. However, two impurity phases γ-Nd2S3-X and Nd2O2S appear in the Nd10S14O samples treated at temperatures above 1620 ± 20 °C.
For samples of the Nd10S14O phase annealed in an argon atmosphere at temperatures of 1050, 1400, 1580 °C, a regular decrease in the unit cell parameters and optical band gap was recorded: 1050 °C a = 15.06291(28), c = 19.97864(35), Eg = 2, 63 eV, 1400 °C a = 15.04779(36), c = 19.97160(44), Eg = 2.64 eV; 1580 °C a = 15.03532(48), c = 19.94984(60), Eg = 2.51 eV. The microhardness of Nd10S14O is H = 549 ± 10 HV. The Nd2O2S phase has H = 593 ± 4 HV, Eg = 4.28 eV.
The phase diagram of the Nd2S3 - Nd2O3 system from 1000 °C to the melt was constructed. The Nd2O2S phase melts congruently at 2050 ± 30 °C. Eutectics with coordinates 23 mol. % Nd2O3 (0.3484 Nd10S14O + 0.6516 Nd2O2S), t = 1553 ± 1.8°С; ΔH = 187 ± 19 J/g; 82 mol. % Nd2O3; (0.54 Nd2O2S + 0.46 Nd2O3), t = 1970 ± 30°С were obtained. The liquidus of the Nd2S3 - Nd2O3 system was built according to DSC data and calculated using the Redlich-Kister equation. The melting enthalpy of Nd2O2S ΔH = 67 kJ/mol was calculated using the Schroeder equation.
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•The thermal characteristics and optical properties of the sulfide and oxysulfide phases in the system Nd2S3 - Nd2O3 were determined.•A congruent melting peak at temperature 1801 ± 4.9 °C with ΔH = 65.2 ± 6.7 kJ/mol was detected for the Nd2S3 compound by the DSC method. The characteristics of the α-Nd2S3 .→ γ-Nd2S3 polymorphic transition are t = 1183 ± 1.8°С, and ΔH = 7.5 ± 0.3 kJ/mol. The microhardness of the phases is: α-Nd2S3H = 451 ± 4 HV; γ-Nd2S3H = 531 ± 4 HV.•It was found by the TG that the Nd10S14O phase thermally dissociates at temperatures above 1400 °C. The mass loss is 0.5 mass % at 1580 °C and 1.0 mass % at 1620 °C, but the samples remain single-phase ones after cooling.•For samples of the Nd10S14O phase annealed in an argon atmosphere at temperatures of 1050, 1400, 1580 °C, a regular decrease in the unit cell parameters and optical band gap was recorded:•The phase diagram of the Nd2S3 - Nd2O3 system from 1000 °C to the melt was constructed. The Nd2O2S phase melts congruently at 2050 ± 30 °C. Eutectics with coordinates 23 mol. % Nd2O3 (0.3484 Nd10S14O + 0.6516 Nd2O2S), t = 1553 ± 1.8°С; ΔH = 187 ± 19 J/g; 82 mol. % Nd2O3; (0.54 Nd2O2S + 0.46 Nd2O3), t = 1970 ± 30°С were obtained.
An analysis of spatially localized and time-periodic vibrational modes (discrete breathers – DBs) is carried out. It is found out that the discreteness and nonlinearity of the medium are the main ...necessary conditions for the existence of discrete breathers, and these conditions are satisfied in the crystal lattice. The role of DBs in the formation of the physical properties of crystals is discussed. The arguments are presented in favor of the fact that this role increases many times in the states far from thermodynamic equilibrium and in the lowstability pre-transitional states of the crystal lattice.
Two-micron lasing is obtained on the 5I7 → 5I8 transition of Ho3+ ions in ZrO2 − Y2O3 −Ho2O3 crystals upon resonance pumping into the 5I7 level of these ions by a pulsed laser based on a Tm : LiYF4 ...crystal. The efficiency of conversion of pump radiation incident on the crystal to laser radiation and the slope lasing efficiency at a pulse duration of 8 ms and a pulse repetition rate of 10 Hz were 25% and 28%, respectively.
Based on the results of processing an interferometric pair of PALSAR-2 L-band synthetic aperture radar (SAR) images taken over the territory of the Bureya landslide in May 2019 and May 2020 from the ...ALOS-2 satellite, a new unstable surface region has been discovered. The average monthly rate of soil displacement was estimated to be up to 1 cm/month along the slope surface at the site of the formation of a new scarp. It is noted that the materials of interferometric processing of archival data did not previously reveal any movements of the slope surface in this place. The most probable reason for the activation of the landslide process in the new area is named: a violation of stability as a result of the descent in December 2018 of the underlying landslide body.
A complex regional analysis of data obtained from GPS observations at ground-based satellite radio signal receiving stations for the largest (M 7.0) earthquake that occurred in the beginning of ...January 2010 on Haiti is carried out. The radio signal receiving stations jointly used in this work belong to two global networks (IGS and UNAVCO). A vast statistical data set spatiotemporal measurements, namely, more than 5 million of radio signal phase readings, has been processed. Differentiated software-algorithmic methods of processing satellite radio signal data allowed us to identify and consider the characteristics of the spatial and temporal scales of ionospheric irregularities. Using geophysical analysis, the detected inhomogeneous structures of the ionosphere are referenced to the topographical map of the area. Statistical characteristics of the deviations and distributions of the distinguished ionospheric structures from boundaries of the lithospheric plates are calculated. The seismic events were developed under quiet geomagnetic conditions and the absolute value of the
Dst
index did not exceed 20 nT, which made it possible to consider ionospheric manifestations of atmosphere–lithosphere interactions during the monitoring period. To make the geophysical analysis reliable, data of the updated digital model of lithospheric plate boundaries are used.
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