Microstructure, mechanical and tribological properties of advanced layered WN/MeN (Me = Zr, Cr, Mo, Nb) nanocomposite coatings

Due to the increased demands for drilling and cutting tools working at extreme machining conditions, protective coatings are extensively utilized to prolong the tool life and eliminate the need for lubricants. The present work reports on the effect of a second MeN (Me = Zr, Cr, Mo, Nb) layer in WN-based nanocomposite multilayers on microstructure, phase composition, and mechanical and tribological properties. The WN/MoN multilayers have not been studied yet, and cathodic-arc physical vapor deposition (CA-PVD) has been used to fabricate studied coating systems for the first time. Moreover, first-principles calculations were performed to gain more insight into the properties of deposited multilayers. Two types of coating microstructure with different kinds of lattices were observed: (i) face-centered cubic (fcc) on fcc-W2N (WN/CrN and WN/ZrN) and (ii) a combination of hexagonal and fcc on fcc-W2N (WN/MoN and WN/NbN). Among the four studied systems, the WN/NbN had superior properties: the lowest specific wear rate (1.7 × 10^-6 mm^3/Nm) and high hardness (36 GPa) and plasticity index H/E (0.93). Low surface roughness, high elastic strain to failure, Nb2O5 and WO3 tribofilms forming during sliding, ductile behavior of NbN, and nanocomposite structure contributed to high tribological performance. The results indicated the suitability of WN/NbN as a protective coating operating in challenging conditions

Non-Standard Errors

In statistics, samples are drawn from a population in a data-generating process (DGP). Standard errors measure the uncertainty in estimates of population parameters. In science, evidence is generated to test hypotheses in an evidence-generating process (EGP). We claim that EGP variation across researchers adds uncertainty: Non-standard errors (NSEs). We study NSEs by letting 164 teams test the same hypotheses on the same data. NSEs turn out to be sizable, but smaller for better reproducible or higher rated research. Adding peer-review stages reduces NSEs. We further find that this type of uncertainty is underestimated by participants

Pandemic and sanctions as risk factors for the sustainable development of transport systems

This article analyzes approaches to determining external factors affecting the transport industry, as well as the degree of influence of the most significant factors, such as the Covid-19 pandemic and sanctions pressure, on passenger traffic. The development of the transport industry is influenced by various factors, both global and internal. At the same time, it can be noted that there is a correlation between these groups of factors, which makes it possible to weaken the negative pressure of one group of influence factors by strengthening the other group. Based on the application of monographic, economic-mathematical, statistical and expert methods, the indicators characterizing the transport industry are analyzed. The growth rates of indicators are calculated: passenger traffic, passenger capacity, passenger traffic growth index. The influence of external factors (pandemic and sanctions) on passenger transportation was determined using passenger traffic indicators and the passenger traffic growth index. It is concluded that the pandemic and sanctions have significantly affected the dynamics of passenger transportation and the transport industry as a whole. Moreover, the degree of influence of each of these factors is different. Using the example of air transportation, the global and Russian trends of the pandemic's impact on passenger traffic are determined

Two decades of active layer thickness monitoring in northeastern Asia

This study summarizes seasonal thawing data collected in different permafrost regions of northeast Asia over the 1995–2018 period. Empirical observations were undertaken under the Circumpolar Active Layer Monitoring (CALM) program at a range of sites across the permafrost landscapes of the Yana-Indigirka and Kolyma lowlands and the Chukotka Peninsula, and supplemented with 10 years of observations from volcanic mountainous areas of the Kamchatka Peninsula. Thaw depth observations, taken using mechanical probing at the end of the thawing season, and ground temperature measurements, were analyzed with respect to air temperatures trends. The data from 24 sites (16 in the Indigirka-Kolyma region, 5 in Chukotka and 3 in Kamchatka) reveal different reactions of the active layer thickness (ALT) to recent changes in atmospheric climate. In general, there is a positive relation between ALT and summer air temperatures. Since the early 2000s positive ALT anomalies (compared with mean data from all sites) prevail in the Kolyma and Chukotka area, with only one alas site showing a negative ALT trend. The only active site in the Kamchatka Mountains shows no significant thaw depth changes over the period of observation. Two other Kamchatka sites were affected during a volcanic eruption in 2012