323,356 research outputs found
Doring, H W, Q127625
No full textThis record was harvested from a previous catalogue system and will be withdrawn in 2025. Information in this record may be superseded or incomplete. Visit this record in UMA's new catalogue at: https://archives.library.unimelb.edu.au/nodes/view/382313Surname: DORING. Given Name(s) or Initials: H W. Military Service Number or Last Known Location: Q127625. Missing, Wounded and Prisoner of War Enquiry Card Index Number: 47212.213407
Item: [2016.0049.14606] "Doring, H W, Q127625
Drilling with ultrashort laser pulses at high repetition rates
No full textUltrashort laser pulses offer extraordinary precision in microprocessing a variety of materials, especially metals. Thermal and mechanical damage can be minimized by working at fluences not too far above the ablation threshold. However, this comes at the expense of low ablation rates and thus high processing times. A scaling of processing speed by increasing the fluence results in degradation in quality. Therefore, in this chapter we investigate the potential for scaling the processing speed by increasing the pulse repetition rate to several 100 kHz up to the MHz regime with average laser powers of up to 100 W exemplary for percussion drilling of metals. Limiting factors like particle shielding and heat accumulation are identified, their dependence on laser parameters as well as material properties are discussed and options for drilling at significantly improved speeds are highlighted
High repetition rate ultrashort pulse micromachining with fiber lasers
No full textDespite its advantages with respect to precision, ultrashort pulse micromachining often suffers from a low processing speed. We will discuss the opportunities for high repetition rate and high average power ultrafast fiber lasers to overcome these problems. © OSA / FILAS 2011
Heavy quark free energies and screening at finite temperature and non-zero baryon chemical potential
No full textDoring M, Ejiri S, Kaczmarek O, Karsch F, Laermann E. Heavy quark free energies and screening at finite temperature and non-zero baryon chemical potential. In: PoS. Vol LAT2005. 2006: 193
Critical performance aspects of ultrashort pulse laser materials processing at high repetition rates and average powers
No full textAn experimental investigation is presented on the ultrashort pulse laser drilling of different metals with diverse thermal properties in the high repetition rate and high average power regime. An Ytterbium-doped fiber CPA system was used, providing pulse energies and repetition rates up to 70 μJ and 1 MHz, respectively. It has been found that at a few hundred kilohertz particle shielding causes a decrease of the ablation rate, depending on the pulse energy. At higher repetition rates, the heat accumulation effect overbalances particle shielding, but significant melt ejection affects the hole quality. The influence, in this regime, of pulse duration (800 fs to 19 ps) and wavelength (1030 nm and 515 nm) on the drilling efficiency and on the achievable precision have been further experimentally studied
The Sedimentary Context of Open-Air Archaeology: A Case Study in the Western Cape’s Doring River Valley, South Africa
No full textDespite the wealth of Late Pleistocene archaeology that exists across southern Africa’s open landscape, it is routinely neglected in favour of rock shelter (re)excavation, biasing interpretation of human–environment interaction. This is compounded by the scarcity of open-air studies that use geoarchaeological methods to investigate the history and processes involved in their formation. The open-air archaeology of the Doring River Valley is an example of this, despite nearly a decade of dedicated study and publication. Consequently, there remains a limited and untested understanding of the valley’s formation history. This paper rectifies this by providing a sedimentary context for the surface archaeology exposed across one of the Doring River Valley’s artefact-baring localities, Uitspankraal 7 (UPK7). Characterisation, particle size, mineralogical, morphometric, and geophysical analysis of UPK7′s sand mantle resulted in the identification of four artefact-bearing sedimentary units, the aeolian and pedogenic processes involved in their formation, and their proposed order of deposition. This provides a stratigraphic, taphonomic, and environmental context against which chronometric dating and an analysis of the taphonomic, spatio-temporal, and technological composition of UPK7′s surface archaeology can be compared. This work is the first vital step towards understanding the depositional and behavioural history of a landscape, irrespective of context type
Diffusive author(s), cohesive author: Analysis of S/N (1994)
No full textThis study indicates the ways in which various aspects of the author(s) are brought forth in Dumb type’s performance art, the S/N production. Previous research has suggested a non-hierarchical organization of Dumb type and the absence of a “privileged author” in Dumb type’s collaborative work, S/N. However, the results that I have investigated from member’s interviews on the creative process of S/N along with my analysis of the recorded images of S/N, indicate a different aspect of the author(s). First, S/N was created through, so to speak, the collective ideas of the members of Dumb type. Further, S/N has at least nine quotations from previous performances, installations, and printed writings, besides the work-in-progress technique. Explicating one of the “author functions” as given by Michel Foucault, each text has plural subjects of the author. However, it has been revealed from members’ interviews that Teiji Furuhashi had a decision-making role in selecting the members’ ideas within the performance. Since then, S/N has had plural subjects of creation; however, Furuhashi is one of the subjects of creation along with the “privileged author.” S/N has plural authors (diffusive authors) yet at the same time, it has a “privileged author,” Teiji Furuhashi (cohesive author)
Microdrilling of metals using femtosecond laser pulses and high average powers at 515 nm and 1030 nm
No full textWe investigate the microdrilling of metals (stainless steel, copper and tungsten) for two different wavelengths, 1030 nm and 515 nm, in the regime of femtosecond laser pulses. An ytterbium-doped fibre CPA system provides high pulse energies (up to 70 μJ) and high repetition rates (up to 800 kHz), corresponding to high average powers of about 50 W, for this experimental study. © 2010 Springer-Verlag
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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