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RISS 인기검색어
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- 저자 : Bernd Engel (검색결과 2 건)
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Re-engineering of Rotary Draw Bending Machines: a Survey of Manufacturers and Users
Bernd Engel,Sara Salman Hassan Al-Maeeni 한국정밀공학회 2020 International Journal of Precision Engineering and Vol.7 No.1
Natural resources limitation and new legislative rules for waste reduction prompt the manufacturers of machine tools to be responsible for taking back their obsolete machines of high value-added, and use sustainable disposal methods such as machine retrofitting, rebuilding, or remanufacturing. Re-engineering of machine tools, concerning design development and failure analysis, is a concept enables and facilitates the implementation of the sustainable disposal methods. This paper aims to identify the re-engineering motivations, barriers, and required design modifications. As stated in a survey conducted among users and manufacturers of rotary draw bending machines, as a case study, economic benefits, use of the same tooling, environmental protection are the primary motivations, while spare parts unavailability, old parts wear and damage, and the high price of replacement parts are the most serious challenges make these machines more difficult to reuse. Furthermore, the required design modifications for designing reusable machines were highlighted in this paper. Additionally, measures for improving the accuracy, capacity, and performance of the studied machine are evaluated according to the survey results, and consequently, an investigation approach for mechanical failure analysis was created. In conclusion, it is observed that the results of the studied case confirmed the survey findings.
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Lee, Ji-Eun,Stepanenko, Vladimir,Yang, Jaesung,Yoo, Hyejin,Schlosser, Felix,Bellinger, Daniel,Engels, Bernd,Scheblykin, Ivan G.,Wü,rthner, Frank,Kim, Dongho American Chemical Society 2013 ACS NANO Vol.7 No.6
<P>Properties of a series of acetylene-linked perylene bisimide (PBI) macrocycles with different ring size composed of three to six PBI dyes were investigated by atomic force microscopy (AFM) and single-molecule fluorescence spectroscopy in a condensed phase. It was demonstrated that the structures of PBI cyclic arrays (C<I>N</I>s, <I>N</I> = 3, 4, 5, and 6) become distorted with increasing the ring size through molecular dynamics (MD) simulations (PM6-DH2 method) and AFM height images of C<I>N</I>s on highly ordered pyrolytic graphite (HOPG) surface. The MD simulations showed that only <B>C5</B> and <B>C6</B> rings are highly flexible molecules whose planarization goes along with a significant energetic penalty. Accordingly, both molecules did not show ordered adlayers on a HOPG surface. In contrast, <B>C3</B> and <B>C4</B> are far more rigid molecules leading to well-ordered hexagonal (<B>C3</B>) and rectangular (<B>C4</B>) 2D lattices. At the single-molecule level, we showed that the fluorescence properties of single C<I>N</I>s are affected by the structural changes. The fluorescence lifetimes of C<I>N</I>s became shorter and their distributions became broader due to the structural distortions with increasing the ring size. Furthermore, the C<I>N</I>s of smaller ring size exhibit a higher photostability and an efficient excitation energy transfer (EET) due to the more well-defined and planar structures compared to the larger C<I>N</I>s. Consequently, these observations provide evidence that not only PBI macrocycles are promising candidates for artificial light-harvesting systems, but also the photophysical properties of C<I>N</I>s are strongly related to the structural rigidity of C<I>N</I>s.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/ancac3/2013/ancac3.2013.7.issue-6/nn400616u/production/images/medium/nn-2013-00616u_0012.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/nn400616u'>ACS Electronic Supporting Info</A></P>
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