Pulsed current arcwelding Research Papers (original) (raw)

The aim of this work is to investigate the influence of the welding process parameters on the weld bead geometry, microstructure characteristics, and mechanical properties of weldments curried out using TIG welding with pulsed/non pulsed current processes. The cooling state was introduces as an input parameter to investigate the main effects on the structure morphology and thereby the mechanical property. In this work the selected pulse frequency levels were 5-500 Hz in order to show the effect of low and high frequencies on the weldment characteristics of AISI 304L plates using filler metal of ER 308LSi. In this work, three levels four factors Taguchi L9 orthogonal array was used to analyze the aspect ratio of the welded specimens. Taguchi analysis was performed for the main effects plot to optimize the process parameters. Furthermore, the microstructure evolution has been investigated. Thus key findings of this work clarified that the pulse frequency has significant effect on the breaking of the dendrite arms during welding process and so strongly affects on the tensile strength. The cooling state also affects on the microstructure texture and thereby, the mechanical properties. The most important factor affects the bead geometry and aspect ratio is the travel speed.

Archivematica is an open-source and non-commercial digital preservation system, that was cho-sen and installed by the National Library of Wales to explore the ingest and preservation of digital data-objects, as part of the digital preservation ambitions of the Archives and Records Council Wales. The aim of the dissertation is to comprehend the operating principles of Archivematica 1.5 and evaluate the transfer and ingest functionality for digital data-objects of Local Authorities. This dissertation applies multiple research methods to cross-validate the findings on the Ar-chivematica ingest functionality and the according metadata and rights management. In addition to a comprehensive literature review, and the technical analysis of the Archivematica ingest, a mostly qualitative data collection captures the current situation in Welsh digital preservation in-stitutions regarding metadata and rights management. The final research method targets the criteria-based evaluation of the Archivematica ingest according to the recommendations of the Producer-Archive Interface Methodology Standard. The results show, that Archivematica pro-vides interfaces to enter descriptive metadata compliant to Dublin Core, and administrative metadata compliant to PREMIS. To create a submission ready data-set, the data-objects benefit from descriptive metadata input with the aid of a CSV-file. The automatic extraction and pro-cessing of descriptive metadata from a CSV-file is enabled by Archivematica 1.5, however admin-istrative metadata cannot be handled in that manner yet. The small-scale purposive data collec-tion through executing a mostly open-ended questionnaire revealed that copyright and license regulation are predominant. The need for a digital preservation system and capturing metadata is bridged by applying cataloguing software. The criteria based evaluation of the ingest function-ality of Archivematica confirmed the good quality of the technical architecture of this digital preservation system. Archivematica’s ability to be adjusted and extended by other software for transfer and pre-ingest storage, and access is beneficial for the adaption to current needs and circumstances of the archive.