Arc Welding-Laser Shock Forging Process for Improving the Mechanical Properties of the Fe-Cr-C Cladded Layer

While parts can be repaired via arc welding (AW), it is usually necessary to add some types of excitation method to improve the mechanical properties of the cladded layer. Here, the arc welding-laser shock forging (AW-LSF) was used to repair Q235 steel pipes (Fe-Cr-C alloy was used as the cladding material). The effects of the welding current (WC), welding speed (WS), and laser shock frequency (LSF) on the geometry and microhardness of the weld bead were studied. The AW-LSF and AW repair processes were compared. The results demonstrate that the bead width (W) and penetration depth (D) increase with the WC, while the weld height (H) decreases with the WC. The H, W, and D all decrease with the WS; W and D increase with the LSF; and H decreases with the LSF. As the WC increases, the hardness of the fusion zone (FZ) and partial fusion zone (PFZ) decreases significantly, while the hardness of the heat-affected zone (HAZ) remains nearly unchanged. As the WS increases, the hardness of the PFZ decreases, while the hardness of the FZ and HAZ remains nearly unchanged. With the increase of the LSF, the hardness of the PFZ, FZ, and HAZ increases. Compared with AW, the AW-LSF can reduce the cladded layer crystal grain size, increase the hardness, and improve the sliding wear resistance.

Habitat loss, predation pressure and episodic heat-shocks interact to impact arthropods and photosynthetic functioning of microecosystems

Ecosystems face multiple, potentially interacting, anthropogenic pressures that can modify biodiversity and ecosystem functioning. Using a bryophyte–microarthropod microecosystem we tested the combined effects of habitat loss, episodic heat-shocks and an introduced non-native apex predator on ecosystem function (chlorophyll fluorescence as an indicator of photosystem II function) and microarthropod communities (abundance and body size). The photosynthetic function was degraded by the sequence of heat-shock episodes, but unaffected by microecosystem patch size or top-down pressure from the introduced predator. In small microecosystem patches without the non-native predator, Acari abundance decreased with heat-shock frequency, while Collembola abundance increased. These trends disappeared in larger microecosystem patches or when predators were introduced, although Acari abundance was lower in large patches that underwent heat-shocks and were exposed to the predator. Mean assemblage body length (Collembola) was reduced independently in small microecosystem patches and with greater heat-shock frequency. Our experimental simulation of episodic heatwaves, habitat loss and non-native predation pressure in microecosystems produced evidence of individual and potentially synergistic and antagonistic effects on ecosystem function and microarthropod communities. Such complex outcomes of interactions between multiple stressors need to be considered when assessing anthropogenic risks for biota and ecosystem functioning.

Stochastic generator of earthquakes in French territories

<p>Both French mainland and Lesser Antilles are characterized by sparse earthquake catalogues respectively due to the low-to-moderate seismic activity and the low recording historical depth. However, it is known that major earthquakes could strike French mainland (e.g. Ligure in 1887 or Basel in 1356) and even more French Lesser Antilles (e.g. Guadeloupe 1943 or Martinique 1839). Assessing seismic hazard in these territories is necessary to support building codes and prevention actions to population. One approach to estimate seismic hazard despite lack of data is to generate a set of plausible seismic scenarios over a large time span. A generator of earthquakes is thus presented in this paper. Its first step is to generate only main shocks. The second step consists of trigger aftershocks related to main shocks.<br>To draw the time occurrence of main shocks, original draw of frequencies and year-by-year summation of it is proceeded. The frequencies are drawn, for each magnitude step, in probability density functions computed through the inter event time method (Hainzl et al. 2006). By propagating magnitude uncertainties contained in the initial catalogue through a Monte Carlo Markov Chain, each magnitude step has not only one main shock frequency but a distribution of it. Once a main shock is temporally drawn, its 2D location is drawn thanks to the cumulative seismic moment recorded on each 5x5 km cell in the French territories. A seismotectonic zoning is used to limit both the spatial distribution and magnitude of large earthquakes. Finally, the other parameters (strike, dip, rake and depth) are drawn in ranges of values depending on the seismotectonic zone where the main shock is located. <br>For purpose of trigger aftershocks from the main shocks, an approximation of the Bath law (Richter 1958; Båth 1965) is proceeded during the computation of the frequency – magnitude distributions. Thus, for each magnitude step, an α–value distribution is obtained in which, for each main shock an α–value is drawn. In this way, the maximal magnitude of triggered aftershocks is known.</p>

Trends in time in the management of the implantable cardioverter defibrillator in the last phase of life: a retrospective study of medical records

Background: The implantable cardioverter defibrillator (ICD) might give unwanted shocks in the last month of life. Guidelines recommend deactivation of the ICD prior to death. Aims: The aims of this study were to examine trends in time (2007–2016) in how and when decisions are made about ICD deactivation, and to examine patient- and disease-related factors which may have influenced these decisions. In addition, care and ICD shock frequency in the last month of life of ICD patients are described. Methods: Medical records of a sample of deceased patients who had their ICD implanted in 1999–2015 in a Dutch university ( n = 308) or general ( n = 72) hospital were examined. Results: Median age at death was 71 years, and 88% were male. ICD deactivation discussions increased from 6% for patients who had died between 2007 and 2009 to 35% for patients who had died between 2013 and 2016. ICD deactivation rates increased in these periods from 16% to 42%. Presence of do-not-resuscitate (DNR) orders increased from 9% to 46%. Palliative care consultations increased from 0% to 9%. When the ICD remained active, shocks were reported for 7% of patients in the last month of life. Predictors of ICD deactivation were the occurrence of ICD deactivation discussions after implantation (OR 69.30, CI 26.45–181.59), DNR order (OR 6.83, CI 4.19–11.12), do-not-intubate order (OR 6.41, CI 3.75–10.96), and palliative care consultations (OR 8.67, CI 2.76–27.21) Conclusion: ICD deactivation discussions and deactivation rates have increased since 2007. Nevertheless, ICDs remain active in the majority of patients at the end of life, some of whom experience shocks.