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The Cr-plated coating inside a gun barrel can effectively improve the barrel’s erosion resistance and thus increase the service life. However, due to the cyclic thermal load caused by high-temperature gunpowder, micro-element damage tends to occur within the Cr coating/steel substrate interface, leading to a gradual deterioration in macro-mechanical properties for the material in the related region. In order to mimic this cyclic thermal load and, thereby, study the thermal erosion behavior of the Cr coating on the barrel’s inner wall, a laser emitter is utilized in the current study. With the help of in-situ tensile test and finite element simulation results, a shear stress distribution law of the Cr coating/steel substrate and a change law of the interface ultimate shear strength are identified. Studies have shown that the Cr coating/steel substrate interface’s ultimate shear strength has a significant weakening effect due to increasing temperature. In this study, the interfacial ultimate shear strength decreases from 2.57 GPa (no erosion) to 1.02 GPa (laser power is 160 W). The data from this experiment is employed to establish a Cr coating/steel substrate interface shear damage model. And this model is used to predict the flaking process of Cr coating by finite element method. The simulation results show that the increase of coating crack spacing and coating thickness will increase the service life of gun barrel.

Thermal erosion is a major mechanism of permafrost degradation, resulting in characteristic landforms. We inventory thermo‐erosional valleys in ice‐rich coastal lowlands adjacent to the Siberian Laptev Sea based on remote sensing, Geographic Information System (GIS), and field investigations for a first regional assessment of their spatial distribution and characteristics. Three study areas with similar geological (Yedoma Ice Complex) but diverse geomorphological conditions vary in valley areal extent, incision depth, and branching geometry. The most extensive valley networks are incised deeply (up to 35 m) into the broad inclined lowland around Mamontov Klyk. The flat, low‐lying plain forming the Buor Khaya Peninsula is more degraded by thermokarst and characterized by long valleys of lower depth with short tributaries. Small, isolated Yedoma Ice Complex remnants in the Lena River Delta predominantly exhibit shorter but deep valleys. Based on these hydrographical network and topography assessments, we discuss geomorphological and hydrological connections to erosion processes. Relative catchment size along with regional slope interact with other Holocene relief‐forming processes such as thermokarst and neotectonics. Our findings suggest that thermo‐erosional valleys are prominent, hitherto overlooked permafrost degradation landforms that add to impacts on biogeochemical cycling, sediment transport, and hydrology in the degrading Siberian Yedoma Ice Complex., Christiane Nüsslein‐Volhard Foundation, European Research Council http://dx.doi.org/10.13039/501100000781, German Academic Exchange Service DAAD P.R.I.M.E., Helmholtz‐Gemeinschaft http://dx.doi.org/10.13039/501100001656, Polar Geospatial Center, NSF‐OPP awards, RapidEye Science Archive (RESA), Russian Foundation for Basic Research http://dx.doi.org/10.13039/501100002261, Studienstiftung des Deutschen Volkes http://dx.doi.org/10.13039/501100004350, Universität Potsdam http://dx.doi.org/10.13039/501100004238, BMBF KoPf

Arctic warming is leading to substantial changes to permafrost including rapid Degradation of ice and ice-rich coasts and riverbanks. In this study, we present and evaluate a high spatiotemporal resolution three-year time series of X-Band microwave satellite data from the TerraSAR-X (TSX) satellite to quantify cliff-top erosion (CTE) of an ice-rich permafrost riverbank in the central Lena Delta. We apply a threshold on TSX backscatter images and automatically extract cliff-top lines to derive intra- and inter-annual CTE. In order to examine the drivers of erosion we statistically compare CTE with climatic baseline data using linear mixed models and analysis of variance (ANOVA). Our evaluation of TSX-derived CTE against annual optical-derived CTE and seasonal in situ measurements showed good agreement between all three datasets. We observed continuous erosion from June to September in 2014 and 2015 with no significant seasonality across the thawing season. We found the highest net annual cliff-top erosion of 6.9 m in 2014, in accordance with above-average mean temperatures and thawing degree days as well as low precipitation. We found high net annual erosion and erosion variability in 2015 associated with moderate mean temperatures but above average precipitation. According to linear mixed models, climate parameters alone could not explain intra-seasonal erosional patterns and additional factors such as ground ice content likely drive the observed erosion. Finally, mean backscatter intensity on the cliff surface decreased from -5.29 to -6.69 dB from 2013 to 2015, respectively, likely resulting from changes in surface geometry and properties that could be connected to partial slope stabilization. Overall, we conclude that X-Band backscatter time series can successfully be used to complement optical remote sensing and in situ monitoring of rapid tundra permafrost erosion at riverbanks and coasts by reliably providing information about intra-seasonal dynamics.

The objectives were (i) to evaluate the relationship between recent climate change and extreme hydrological events and (ii) to characterize the behavior of hydrological events along the Alazeya River. The warming rate of air temperature observed at the meteorological station in Chersky was 0.0472 °C·year−1, and an extraordinary increase in air temperatures was observed in 2007. However, data from meteorological stations are somewhat limited in sparsely populated regions. Therefore, this study employed historical remote sensing data for supplementary information. The time-series analysis of the area-averaged Global Precipitation Climatology Project (GPCP) precipitation showed a positive trend because warming leads to an increase in the water vapor content in the atmosphere. In particular, heavy precipitation of 459 ± 113 mm was observed in 2006. On the other hand, the second-highest summer National Oceanic and Atmospheric Administration (NOAA) Advanced Very High Resolution radiometer (AVHRR) brightness temperature (BT) was observed in 2007 when the highest air temperature was observed in Chersky, and the anomaly from normal revealed that the summer AVHRR BTs showed mostly positive values. Conversely, riverbank, lakeshore and seashore areas were much cooler due to the formation, expansion and drainage of lakes and/or the increase in water level by heavy precipitation and melting of frozen ground. The large lake drainage resulted in a flood. Although the flooding was triggered by the thermal erosion along the riverbanks and lakeshores—itself induced by the heat wave in 2007—the increase in soil water content due to the heavy precipitation in 2006 appeared to contribute the magnitude of flood. The flood was characterized by the low streamflow velocity because the Kolyma Lowlands had a very gentle gradient. Therefore, the flood continued for a long time over large areas. Information based on remote sensing data gave basic insights for understanding the mechanism and behavior of climate-induced extreme hydrologic events.