9 research outputs found
Features of the process of laser welding of cast iron with steel
The article presents the results of research on laser welding of cast iron with steel on a robotic laser technological complex. A system of technical vision for precision focusing of laser radiation on the joint of welded elements is presented, which provides control of the movement of the laser beam along the welded joint and adjustment of the radiation power, depending on the temperature of the joint. The welding process is carried out in a protective atmosphere of inert gases. Rough guidance of the beam is carried out by the robotic complex until the point "start of welding"falls into the field of view of the technical vision system, which is built into the process head. Precision positioning of the beam focus on the seam is provided by turning the focusing lens to a certain angle by a piezo actuator. The results of metallographic studies of the welded seam of cast iron and steel are presented
The laser heat-treatment process control by the non-stationary convective heat exchange modeling
© 2020 IOP Publishing Ltd. All rights reserved. Various technological processes allow to obtain high quality indicators, such as laser cutting, welding, hardening, etc. The article presents the results of modeling for laser cutting of thick-walled structures. The creation of computational tools for express analysis in a mathematical setting and a quantitative assessment of temperature fields in spatially variable and non-stationary conditions of laser exposure are of undoubted practical interest to minimize experimental costs
Determination of the Convective Heat-Exchange Coefficient in Inner Channels of Light-Absorbing Heat-Exchange Panels of Flat-Plate Solar Water-Heating Collectors Based on the Results of Their Short-Term Thermal Testing in Full-Scale Conditions
Influence of Ambient Temperature, Wind Speed, Emissivity, and Average Working Temperature of Light-Absorbing Heat-Exchange Panels of Flat-Plate Solar Water-Heating Collectors on Their Thermal Losses Through Translucent Coatings
Body mass index and complications following major gastrointestinal surgery: A prospective, international cohort study and meta-analysis
Aim Previous studies reported conflicting evidence on the effects of obesity on outcomes after gastrointestinal surgery. The aims of this study were to explore the relationship of obesity with major postoperative complications in an international cohort and to present a metaanalysis of all available prospective data. Methods This prospective, multicentre study included adults undergoing both elective and emergency gastrointestinal resection, reversal of stoma or formation of stoma. The primary end-point was 30-day major complications (Clavien–Dindo Grades III–V). A systematic search was undertaken for studies assessing the relationship between obesity and major complications after gastrointestinal surgery. Individual patient meta-analysis was used to analyse pooled results. Results This study included 2519 patients across 127 centres, of whom 560 (22.2%) were obese. Unadjusted major complication rates were lower in obese vs normal weight patients (13.0% vs 16.2%, respectively), but this did not reach statistical significance (P = 0.863) on multivariate analysis for patients having surgery for either malignant or benign conditions. Individual patient meta-analysis demonstrated that obese patients undergoing surgery formalignancy were at increased risk of major complications (OR 2.10, 95% CI 1.49–2.96, P < 0.001), whereas obese patients undergoing surgery for benign indications were at decreased risk (OR 0.59, 95% CI 0.46–0.75, P < 0.001) compared to normal weight patients. Conclusions In our international data, obesity was not found to be associated with major complications following gastrointestinal surgery. Meta-analysis of available prospective data made a novel finding of obesity being associated with different outcomes depending on whether patients were undergoing surgery for benign or malignant disease