Laser welding is used in critical component production when tight tolerances like minimal distortions and residual stresses are required. Laser beam welding offers a lower heat input, a smaller heat affected zone, lower residual stresses, minimum distortions, and greater mechanical joint characteristics than conventional welding does. In order to simulate the laser welding process used on SS316L plates, the Gaussian heat source model was used. The model is developed and simulated with volumetric heat source model with APDL coding using ANSYS. The thermal profiles at the joint cross sections via welded area, interface across joints is taken for the analysis. The maximum temperature was observed at the fusion zone and associated zones. The residual stresses are analysed in the same path and found the stresses are in safe limits of base material. Predicted and experimentally measured residual stresses are close agreement with 10%.

Online teaching–learning methods have been followed by world-class universities for more than a decade to cater to the needs of students who stay far away from universities/colleges. But during the COVID-19 pandemic period, online teaching–learning helped almost all universities, colleges, and affiliated students. An attempt is made to find the effectiveness of online teaching–learning methods for university and college students by conducting an online survey. A questionnaire has been specially designed and deployed among university and college students. About 450 students from various universities, engineering colleges, medical colleges in South India have taken part in the survey and submitted responses. It was found that the following methods promote effective online learning: animations, digital collaborations with peers, video lectures delivered by faculty handling the subject, online quiz having multiple-choice questions, availability of student version software, a conducive environment at home, interactions by the faculty during lectures and online materials provided by the faculty. Moreover, online classes are more effective because they provide PPTs in front of every student, lectures are heard by all students at the sound level of their choice, and walking/travel to reach classes is eliminated.

Using TRNSYS software, a comparison of the energy performances of flat-plate collectors (FPCs) and evacuated-tube collectors (ETCs) in domestic solar water heating systems located in different climate areas was carried out in order to ascertain solar energy utilization. Investigations were carried out on single FPCs and ETCs and also for strings of four panels connected in series. Tests were conducted using simulations for water as heat transfer fluid with a fixed fluid flow rate and varying the temperature of the collector’s returning fluid. The maximum power peak decreases with the increase in the inlet temperature of the fluid to the collector in the FPC. The maximum outlet temperature of the FPC is higher than the ETC, most of the time. The evacuated-tube collector performs better only in cold climate areas. Simulations suggest that the use of the FPC is strongly discouraged in cold climatic areas due to thermal losses, whereas the ETC works well with reduced dispersion of heat. In warm seasons, on the contrary, the FPC takes advantage of the high environmental temperature which heats the fluid. The maximum yearly outlet temperature and useful power peak predicted in different climatic areas were investigated by varying the temperature of the fluid inlet fed to the two strings of four FPCs and ETCs. In all cases, the outlet temperature is higher in the ETC technology.

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