Multiwire submerged arc welding of steel structures

The assembly of large structures made out of thick steel plates requires a welding process by which multiple wires can be used simultaneously. To reproduce these industrial processes in a research environment, OCAS has invested in a multiwire submerged arc welding (SAW) setup. In this multiwire setup, up to five wires in tandem configuration can be used. The objective of this master thesis is to establish a deeper knowledge of process parameters used to weld steel plates in a thickness range of 12,7 up to 25 mm, by means of the submerged arc welding process. Based on literature, a test matrix is composed in which the number of wires, the plate thickness and other weld parameters are the variables. In addition, a specific plate preparation for each plate thickness is derived from the literature. The preformed weld trails will be evaluated on weld bead geometry and metallographic properties. There is further experimental examination required, which will result in the revising of the matrix

A comprehensive study on the microstructure and mechanical properties of arc girth welded joints of spiral welded high strength API X70 steel pipe

In the paper, the effect of welding technology on the microstructure and mechanical properties of girth welded joints was presented. Metallographic examinations based on light microscopy and SEM were conducted on girth welded joints of API X70 steel pipe. Research has shown that microstructure of the heat-affected zone (HAZ) of MMA girth welded joints is not homogeneous and depends on the thermal history of each area during the welding process. Near the fusion line the zone is coarse, and further away there is a fine-grained zone. In the area of root passes the microstructure consists of recrystallized ferrite grains unlike to cap passes where the fine bainitic microstructure can be observed. In the case of MAG girth welded joints, the weld microstructure consists of primary austenite grains. The primary austenite boundaries serve as nucleation sites of ferrite. The microstructure of the HAZ varies continuously from a coarse—to fine-grained microstructure of the base material. The results of mechanical properties of girth welded joints are also presented. The hardness and strength of arc welded joints depend on welding filler materials as well as welding technology. The results of hardness distribution of MMA and MAG girth welded joints confirmed the results of microstructural evaluation

Would you bribe your lecturer?:A quasi-experimental study on burnout and bribery in higher education

Bribery is a complex and critical issue in higher education (HE), causing severe economic and societal harm. Traditionally, most scholarship on HE corruption has focused on institutional factors in developing countries and insights into the psychological and motivational factors that drive HE bribery on the micro-level mechanisms are virtually non-existent. To close this research gap, this study investigates the connection between study-related burnout and university students’ willingness to offer bribes to their lecturers to pass important exams. Conducting a vignette-based quasi-experimental replication study with 624 university students in Germany, Belgium, and the Netherlands we find that university students in three countries differentiate sharply between different shades of bribery and that a majority accept using emotional influence tactics to pass (failed) exams. In contrast, offering a helping hand or money (i.e., darker shades of bribery) to their lecturer was less acceptable. Study-related burnout is associated with a higher likelihood of engaging in these darker shades of bribery and students’ commitment to the public interest is but a weak factor in preventing unethical behavior. In summary, this study provides solid empirical evidence that university students are likely to use emotional influence tactics violating both the ethical codes of conduct and the formalized bureaucratic procedures of HE examination, particularly if they suffer from study-related burnout. However, the accelerating effect of burnout on bribery is conditional in that it only holds for darker shades of bribery. HE institutions may benefit from implementing the four-eye principle and from launching awareness campaigns that enable lecturers to better recognize these tactics and engage students in creating a transparent environment for testing, grading, and collaboration that is resistant to bribery

Plasmon dispersion in metal nanoparticle chains from angle-resolved scattering

We present angle and frequency resolved optical extinction measurements to determine the dispersion relation of plasmon modes on Ag and Au nanoparticle chains with pitches down to 75 nm. The large splitting between transverse and longitudinal modes and the band curvature are inconsistent with reported electrostatic near-field models, and confirm that far-field retarded interactions are important, even for $\lambda/5$-sized structures. The data imply that lower propagation losses, larger signal bandwidth and larger maximum group velocity then expected can be achieved for wave vectors below the light line. We conclude that for the design of optical nanocircuits coherent far-field couplings across the entire circuit need to be considered, even at subwavelength feature sizes.Comment: 4 pages, 4 figures, colo