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The paper proposes a method for calculating the mode of single-pass arc welding depending on the geometric parameters of the T-fillet weld. The authors reveal the dependence of the residual welding stress level on the welding mode, taking into account the stress concentration due to uneven heating and transverse weld shrinkage. Resulting from the comparison of three modes of single-pass arc welding (manual, mechanized, and automatic), the optimal modes that ensure the maximum lifetime of welded structures are determined.

The paper discusses the change of phosphogypsum surface state produced by Apatit (Cherepovetsky branch, Vologda region) during calcination at 298-1173 K. The authors have determined the average size of its crystallites and studied the atomic composition of raw materials and finished composites that include crushed rock fraction (5-10 mm), oil bitumen, and polyethylene terephthalate additive (1.0-1.2 wt. %). The compounds present in calcined phosphogypsum have been analyzed by X-ray diffraction. The granulate was obtained by pelletizing phosphogypsum with a mixture of the above components. The paper presents the assessment of its physical and chemical properties. The granulated composites based on the specified samples of calcined phosphogypsum, bitumen, and melted polyethylene terephthalate waste show great promise for construction road works in European countries in summer and winter, as well as countries with tropical climates.

The authors developed technology for obtaining surface composite materials. This technology includes high-energy mechanical treatment, HVOF in a protective atmosphere, subsequent thermomechanical and thermal treatment of ZrCuNiCoTi, cBNNi3AlSiCCoY layers in a protective atmosphere. The processing allowed to increase the adhesive strength of the surface composites, reduce their porosity and improve their functional and operational properties. Staged methods of heat treatment and plastic deformation of surface layers have been developed. These methods stabilize material structure while reducing residual stresses. On the basis of complex X-ray diffraction and electron microscopic studies, the structural parameters of surface composites were determined. It was shown that the ZrCuNiCoTi alloy is in the austenitic-martensitic state and has a nanocrystalline structure with a grain size of 80–120 nm. Meanwhile, the cBNNi3AlSiCCoY alloy consists of many intermetallic phases and inclusions and has a nanosized structure with a grain size of 100–200 nm. A microhardness study of the surface layers in ZrCuNiCoTi – cBNNi3AlSiCCoY composite showed that thermomechanical treatment increases microhardness. The experimental data were statistically processed. As a result, empirical mathematical dependences of the stress amplitude on cyclic durability were compiled. Mechanical tests included tests of NiCoTiZrHf – cBNCoMo, ZrCuNiCoTi – cBNNi3AlSiCCoY, TiNiZrHfCoCu – cBNCoNiAlY composites for multi-cycle fatigue during bending with rotation.

Global dust storms on Mars are rare1,2but can affect the Martian atmosphere for several months. They can cause changes in atmospheric dynamics and inflation of the atmosphere3, primarily owing to solar heating of the dust3. In turn, changes in atmospheric dynamics can affect the distribution of atmospheric water vapour, with potential implications for the atmospheric photochemistry and climate on Mars4. Recent observations of the water vapour abundance in the Martian atmosphere during dust storm conditions revealed a high-altitude increase in atmospheric water vapour that was more pronounced at high northern latitudes5,6, as well as a decrease in the water column at low latitudes7,8. Here we present concurrent, high-resolution measurements of dust, water and semiheavy water (HDO) at the onset of a global dust storm, obtained by the NOMAD and ACS instruments onboard the ExoMars Trace Gas Orbiter. We report the vertical distribution of the HDO/H2O ratio (D/H) from the planetary boundary layer up to an altitude of 80 kilometres. Our findings suggest that before the onset of the dust storm, HDO abundances were reduced to levels below detectability at altitudes above 40 kilometres. This decrease in HDO coincided with the presence of water-ice clouds. During the storm, an increase in the abundance of H2O and HDO was observed at altitudes between 40 and 80 kilometres. We propose that these increased abundances may be the result of warmer temperatures during the dust storm causing stronger atmospheric circulation and preventing ice cloud formation, which may confine water vapour to lower altitudes through gravitational fall and subsequent sublimation of ice crystals3. The observed changes in H2O and HDO abundance occurred within a few days during the development of the dust storm, suggesting a fast impact of dust storms on the Martian atmosphere.

The detection of methane on Mars has been interpreted as indicating that geochemical or biotic activities could persist on Mars today1. A number of different measurements of methane show evidence of transient, locally elevated methane concentrations and seasonal variations in background methane concentrations2–5. These measurements, however, are difficult to reconcile with our current understanding of the chemistry and physics of the Martian atmosphere6,7, which—given methane’s lifetime of several centuries—predicts an even, well mixed distribution of methane1,6,8. Here we report highly sensitive measurements of the atmosphere of Mars in an attempt to detect methane, using the ACS and NOMAD instruments onboard the ESA-Roscosmos ExoMars Trace Gas Orbiter from April to August 2018. We did not detect any methane over a range of latitudes in both hemispheres, obtaining an upper limit for methane of about 0.05 parts per billion by volume, which is 10 to 100 times lower than previously reported positive detections2,4. We suggest that reconciliation between the present findings and the background methane concentrations found in the Gale crater4would require an unknown process that can rapidly remove or sequester methane from the lower atmosphere before it spreads globally.

Migrating tides dominate the tropical climate on Mars and are known to reach high amplitudes during global dust events (GDE). In this study, we characterize the amplitude, phase and vertical wavelength of the diurnal and semidiurnal migrating tides in Mars' lower atmosphere (up to 50 km) by exploiting temperature vertical profiles retrieved from TIRVIM, an infrared spectrometer onboard the ExoMars Trace Gas Orbiter covering multiple local times. Observations from the Mars Climate Sounder onboard the Mars Reconnaissance Orbiter are used to complement the local time coverage when needed, and to estimate a seasonal trend to subtract from TIRVIM observations. We focus on two time periods in Martian Year 34, near Ls = 150° and near Ls = 200° (during the 2018 GDE). The characteristics of the migrating tides at Ls = 150° agree very well with tidal theory: a downward propagation, amplitudes of typically 2–5 K, and a larger vertical wavelength for the semidiurnal compared to the diurnal mode. Comparisons with model predictions from the Mars Planetary Climate Model reveal an excellent agreement, except for a slightly different phase of the diurnal tide. During the GDE, the tide pattern changes spectacularly: the diurnal tide amplitude reaches 35 K at 65°S and 17 K at 50°N, being vertically trapped up to 10 Pa. The semidiurnal tide is maximum near 20–30°S with an amplitude of 8–12 K. The phase of this mode is tilted with latitude, which was not the case before the storm. This indicates a significant contribution of the asymmetric Hough modes due to hemispheric asymmetry in the dust distribution. Important temperature variations are observed in the Martian atmosphere at diurnal scale. Part of these variations are due to a phenomenon called migrating thermal tides, which take the form of global oscillations with periods that are diurnal, or fractions of a day (half a day period = semidiurnal, a third of a day = terdiurnal, etc). Using satellite observations sampling different local times on Mars, we separated these different components and derived their amplitude and phase (the local time at which these oscillations peak) in particular during the global dust event that occurred in 2018. During this major storm, diurnal temperature variations reached 65 K at high southern latitudes near 25 km altitude between the late morning (minimum of temperature) and late evening (maximum of temperature). We also report on the characteristics of the semidiurnal tide and even the terdiurnal tide, which have been less studied during dust storms. The phase of the semidiurnal tide is not the same at all latitudes, which we interpret as a consequence of the asymmetric dust distribution (more dust in the southern hemisphere). Our results agree with predictions from a Global Climate Model, although some small disagreements are found, calling for future improvements in the model. The characteristics of the migrating tides derived from TIRVIM at Ls = 150° agree with tidal theory and model predictionsDuring the 2018 global dust event (GDE), the diurnal tide reached an amplitude of 35 K at 65°S and we tentatively detect the terdiurnal tideDuring the 2018 GDE, the semidiurnal tide amplitude reached 10 K at 20°S and exhibited a phase tilt with latitude The characteristics of the migrating tides derived from TIRVIM at Ls = 150° agree with tidal theory and model predictions During the 2018 global dust event (GDE), the diurnal tide reached an amplitude of 35 K at 65°S and we tentatively detect the terdiurnal tide During the 2018 GDE, the semidiurnal tide amplitude reached 10 K at 20°S and exhibited a phase tilt with latitude

For more than 8 years the Venus Monitoring Camera (VMC) onboard the Venus Express orbiter performed continuous imaging of the Venus cloud layer in UV, visible and near‐IR filters. We applied the correlation approach to sequences of the near‐IR images at 965 nm to track cloud features and determine the wind field in the middle and lower cloud (49–57 km). From the VMC images that spanned from December of 2006 through August of 2013 we derived zonal and meridional components of the wind field. In low‐to‐middle latitudes (5–65°S) the velocity of the retrograde zonal wind was found to be 68–70 m/s. The meridional wind velocity slowly decreases from peak value of +5.8 ± 1.2 m/s at 15°S to 0 at 65–70°S. The mean meridional speed has a positive sign at 5–65°S suggesting equatorward flow. This result, together with the earlier measurements of the poleward flow at the cloud tops, indicates the presence of a closed Hadley cell in the altitude range 55–65 km. Long‐term variations of zonal and meridional velocity components were found during 1,200 Earth days of observation. At 20° ± 5°S the zonal wind speed increases from −67.18 ± 1.81 m/s to −77.30 ± 2.49 m/s. The meridional wind gradually increases from +1.30 ± 1.82 m/s to +8.53 ± 2.14 m/s. Following Bertaux et al. (2016) we attribute this long‐term trend to the influence from the surface topography on the dynamical process in the atmosphere via the upward propagation of gravity waves that became apparent in the VMC observations due to slow drift of the Venus Express orbit over Aphrodite Terra. VMC near‐IR (965 nm) images of Venus dayside were used to derive atmospheric circulation in the middle cloud layerFor the first time the closed Hadley cell that encompasses the upper cloud layer (55–67 km) was observedZonal and meridional components of wind speed in the Venusian middle cloud demonstrate a connection with the underlying topography

Context. Airglow emissions, such as previously observed from NO and O$_2(a-X)$(0-0) on Venus, provide insight into the chemical and dynamical processes that control the composition and energy balance in the upper atmospheres of planets. The OH airglow emission has been observed previously only in the Earth's atmosphere where it has been used to infer atomic oxygen abundances. The O$_2(a-X)$(0-1) airglow emission also has only been observed in the Earth's atmosphere, and neither laboratory nor theoretical studies have reached a consensus on its transition probability.

Venus is known to have been volcanically resurfaced in the last third of solar system history and to have undergone a significant decrease in volcanic activity a few hundred million years ago. However, fundamental questions remain: Is Venus still volcanically active today, and if so, where and in what geological and geodynamic environment? Here we show evidence from the Venus Express Venus Monitoring Camera for transient bright spots that are consistent with the extrusion of lava flows that locally cause significantly elevated surface temperatures. The very strong spatial correlation of the transient bright spots with the extremely young Ganiki Chasma, their similarity to locations of rift‐associated volcanism on Earth, provide strong evidence for their volcanic origin and suggests that Venus is currently geodynamically active. VMC was able to sound Venus surface through the atmosphere transparency windowTransient bright phenomena were observed in the Ganiki Chasma zoneThey are consistent with hypothesis of lava lakes on the surface

Maximum Satisfiability (MaxSAT) is a well-known optimization version of Propositional Satisfiability (SAT) that finds a wide range of practical applications. This work describes and evaluates the Maximum Satisfiability using the Core-Guided approachsolver (MSCG), which is a robust MaxSATsolver that participated in the MaxSATEvaluation 2014.

The feasibility of compensating for aberrations of the optical-beam initial wavefront by aperture sounding, based on the atmospheric backscatter signal from an additional laser source with a different wavelength, is experimentally studied. It is shown that the adaptive system based on this principle makes it possible to compensate for distortions of the initial beam wavefront on a surface path in atmosphere. Specifically, the beam divergence decreases, while the level of the detected mean backscatter power from the additional laser source increases.

The thermal state of material in the zone of laser action is one of the main integrated parameters to determine the evolution of physicochemical processes and structural phase transformations. The conditions of temperature measurements in laser machining are among the most severe even for noncontact technique of optical pyrometry. From a general point of view, the absence of on-line control and monitoring is one of the main limitations of laser technology integration into modern industry. Data on surface temperature dynamics obtained by pyrometry could be widely used to : (a) understand and optimize the laser processes (i.e. define of the links between surface temperature history and the properties of treated materials) ; (b) create process control on-line including feedback from a pyrometer. The main technical parameters of high speed pyrometer (HSP) are the following : brightness temperature range 1150K (1550K)-3500K (threshold sensitivity depends on selected wavelength) ; error of measurement 1 % ; response time 190 µs ; 200 µm spatial resolution at 350 mm distance of pyrometer from the zone of temperature measurements ; wavelength variation in 2 colour channels from 0.5 to 1.1 µm. The opportunities of actual temperature measurements by high speed high spatial resolution pyrometer system in wide range of laser applications are illustrated by : heat treatment, welding, cladding, and pulsed action.

Key knowledge about planetary composition can be recovered from the study of thermal infrared spectral range datasets. This range has a huge diagnostic potential because it contains diagnostic absorptions from a planetary surface and atmosphere. The main goal of this study is to process and interpret the dataset from the Thermal Infrared channel (TIRVIM) which is part of the Atmospheric Chemistry Suite of the ExoMars2016 Trace Gas Orbiter mission to find and characterize dust and water ice clouds in the atmosphere. The method employed here is based on the application of principal component analysis and target transformation techniques to extract the independent variable components present in the analyzed dataset. Spectral shapes of both atmospheric dust and water ice aerosols have been recovered from the analysis of TIRVIM data. The comparison between our results with those previously obtained on Thermal Emission Spectrometer (TES) data and with previous analysis on TIRVIM data, validates the methodology here applied, showing that it allows to correctly recover the atmospheric spectral endmembers present in the TIRVIM data. Moreover, comparison with atmospheric retrievals on PFS, TES and IRIS data, allowed us to assess the temporal stability and homogeneity of dust and water ice components in the Martian atmosphere over a time period of almost 50 years. The analysis of thermal infrared datasets from planetary bodies is of key importance for the understanding of a planet's climate evolution and history: it contains valuable information about composition, temperature and state of the atmosphere. Moreover, surface properties and the surface‐atmosphere interaction can be studied. Here we investigated new thermal infrared data from the Thermal Infrared channel instrument of the ExoMars Trace Gas Orbiter with the main goal of carefully identifying Martian atmospheric dust and water ice clouds components. A methodology based on principal component and target transformation factor analysis techniques has been applied. Based on our results, this methodology can correctly recover both atmospheric dust and water ice aerosols spectral shapes and their abundances in the Martian atmosphere. First successful application of principal components and target transformation techniques to high‐resolution Thermal Infrared channel (TIRVIM) dataSpectral shapes of both atmospheric dust and water ice clouds are recognized and recoveredTIRVIM data are successfully modeled through a linear combination of the recovered water ice and dust end‐members First successful application of principal components and target transformation techniques to high‐resolution Thermal Infrared channel (TIRVIM) data Spectral shapes of both atmospheric dust and water ice clouds are recognized and recovered TIRVIM data are successfully modeled through a linear combination of the recovered water ice and dust end‐members