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Lock-In Thermography Based NDT of Parts for the Automotive Industry
Bohm, Stefan,Hellmanns, Mark,Backes, Andreas,Dilger, Klaus The Society of Adhesion and Interface 2006 접착 및 계면 Vol.7 No.4
The successful use of adhesively bonded parts depends on the defect-free bond of the components. Therefore it is necessary to detect relevant faults and defects in an early state of the production. A 100% test should be pursued, but especially at complicated structures the detection of defects is not easy. Possible testing methods, which show a high potential for the NDT of adhesively bonded parts, are thermography based NDT methods. At present mainly two different procedures of active thermography are being used: Pulse and Lock-In Thermography. With pulse thermography the examined material is warmed up with a short energy pulse (light, eddy current or ultrasonic pulse) and the heat response is recorded after a certain time. The result is an infrared image which indicates material defects in different depths. This paper presents a variety of images showing the capability of Lock-In Thermography to image subsurface defects. Several examples of adhesives joints qualify the ultrasonic Lock-In-Thermography for the in-process quality control for adhesive bonded components.
Harb Samarah V.,Kolanthai Elayaraja,Backes Eduardo H.,Beatrice Cesar A. G.,Pinto Leonardo A.,Nunes Ana Carolina C.,Selistre-de-Araújo Heloisa S.,Costa Lidiane C.,Seal Sudipta,Pessan Luiz Antonio 한국조직공학과 재생의학회 2024 조직공학과 재생의학 Vol.21 No.2
Background: Poly (lactic acid) (PLA) is a biodegradable polyester that has been exploited for a variety of biomedical applications, including tissue engineering. The incorporation of β-tricalcium phosphate (TCP) into PLA has imparted bioactivity to the polymeric matrix. Methods: We have modified a 90%PLA-10%TCP composite with SiO2 and MgO (1, 5 and 10 wt%), separately, to further enhance the material bioactivity. Filaments were prepared by extrusion, and scaffolds were fabricated using 3D printing technology associated with fused filament fabrication. Results: The PLA-TCP-SiO2 composites presented similar structural, thermal, and rheological properties to control PLA and PLA-TCP. In contrast, the PLA-TCP-MgO composites displayed absence of crystallinity, lower polymeric molecular weight, accelerated degradation ratio, and decreased viscosity within the 3D printing shear rate range. SiO2 and MgO particles were homogeneously dispersed within the PLA and their incorporation increased the roughness and protein adsorption of the scaffold, compared to a PLA-TCP scaffold. This favorable surface modification promoted cell proliferation, suggesting that SiO2 and MgO may have potential for enhancing the bio-integration of scaffolds in tissue engineering applications. However, high loads of MgO accelerated the polymeric degradation, leading to an acid environment that imparted the composite biocompatibility. The presence of SiO2 stimulated mesenchymal stem cells differentiation towards osteoblast; enhancing extracellular matrix mineralization, alkaline phosphatase (ALP) activity, and bone-related genes expression. Conclusion: The PLA-10%TCP-10%SiO2 composite presented the most promising results, especially for bone tissue regeneration, due to its intense osteogenic behavior. PLA-10%TCP-10%SiO2 could be used as an alternative implant for bone tissue engineering application. Background: Poly (lactic acid) (PLA) is a biodegradable polyester that has been exploited for a variety of biomedical applications, including tissue engineering. The incorporation of β-tricalcium phosphate (TCP) into PLA has imparted bioactivity to the polymeric matrix. Methods: We have modified a 90%PLA-10%TCP composite with SiO2 and MgO (1, 5 and 10 wt%), separately, to further enhance the material bioactivity. Filaments were prepared by extrusion, and scaffolds were fabricated using 3D printing technology associated with fused filament fabrication. Results: The PLA-TCP-SiO2 composites presented similar structural, thermal, and rheological properties to control PLA and PLA-TCP. In contrast, the PLA-TCP-MgO composites displayed absence of crystallinity, lower polymeric molecular weight, accelerated degradation ratio, and decreased viscosity within the 3D printing shear rate range. SiO2 and MgO particles were homogeneously dispersed within the PLA and their incorporation increased the roughness and protein adsorption of the scaffold, compared to a PLA-TCP scaffold. This favorable surface modification promoted cell proliferation, suggesting that SiO2 and MgO may have potential for enhancing the bio-integration of scaffolds in tissue engineering applications. However, high loads of MgO accelerated the polymeric degradation, leading to an acid environment that imparted the composite biocompatibility. The presence of SiO2 stimulated mesenchymal stem cells differentiation towards osteoblast; enhancing extracellular matrix mineralization, alkaline phosphatase (ALP) activity, and bone-related genes expression. Conclusion: The PLA-10%TCP-10%SiO2 composite presented the most promising results, especially for bone tissue regeneration, due to its intense osteogenic behavior. PLA-10%TCP-10%SiO2 could be used as an alternative implant for bone tissue engineering application.
Mathias Klaui,Dennis Ilgaz,Lutz Heyne,June-Seo Kim,Olivier Boulle,Christine Schieback,Fabian Zinser,Stephen Krzyk,Mikhail Fonin,Ulrich Rudiger,Dirk Backes,Laura J. Heyderman,T. O. Mentes,A. Locatelli 한국자기학회 2009 Journal of Magnetics Vol.14 No.2
Herein, different concepts for domain wall propagation based on currents and fields that could potentially be used in magnetic data storage devices based on domains and domain walls are reviewed. By direct imaging, we show that vortex and transverse walls can be displaced using currents due to the spin transfer torque effect. For the case of field-induced wall motion, particular attention is paid to the influence of localized fields and local heating on the depinning and propagation of domain walls. Using an Au nanowire adjacent to a permalloy structure with a domain wall, the depinning field of the wall, when current pulses are injected into the Au nanowire, was studied. The current pulse drastically modified the depinning field, which depended on the interplay between the externally applied field direction and polarity of the current, leading subsequently to an Oersted field and heating of the permalloy at the interface with the Au wire. Placing the domain wall at various distances from the Au wire and studying different wall propagation directions, the range of Joule heating and Oersted field was determined; both effects could be separated. Approaches beyond conventional field- and current-induced wall displacement are briefly discussed.
Measurement of atmospheric tau neutrino appearance with IceCube DeepCore
Aartsen, M. G.,Ackermann, M.,Adams, J.,Aguilar, J. A.,Ahlers, M.,Ahrens, M.,Altmann, D.,Andeen, K.,Anderson, T.,Ansseau, I.,Anton, G.,Argü,elles, C.,Auffenberg, J.,Axani, S.,Backes, P.,Bagherpour, American Physical Society 2019 Physical review. D Vol.99 No.3
Constraints on Minute-Scale Transient Astrophysical Neutrino Sources
Aartsen, M. G.,Ackermann, M.,Adams, J.,Aguilar, J. A.,Ahlers, M.,Ahrens, M.,Al Samarai, I.,Altmann, D.,Andeen, K.,Anderson, T.,Ansseau, I.,Anton, G.,Argü,elles, C.,Auffenberg, J.,Axani, S.,Backes, American Physical Society 2019 Physical Review Letters Vol.122 No.5
Search for neutrinos from decaying dark matter with IceCube : IceCube Collaboration
Aartsen, M. G.,Ackermann, M.,Adams, J.,Aguilar, J. A.,Ahlers, M.,Ahrens, M.,Samarai, I. Al,Altmann, D.,Andeen, K.,Anderson, T.,Ansseau, I.,Anton, G.,Argü,elles, C.,Auffenberg, J.,Axani, S.,Backes, Springer Berlin Heidelberg 2018 European Physical Journal C Vol.78 No.10
<P>With the observation of high-energy astrophysical neutrinos by the IceCube Neutrino Observatory, interest has risen in models of PeV-mass decaying dark matter particles to explain the observed flux. We present two dedicated experimental analyses to test this hypothesis. One analysis uses 6 years of IceCube data focusing on muon neutrino ‘track’ events from the Northern Hemisphere, while the second analysis uses 2 years of ‘cascade’ events from the full sky. Known background components and the hypothetical flux from unstable dark matter are fitted to the experimental data. Since no significant excess is observed in either analysis, lower limits on the lifetime of dark matter particles are derived: we obtain the strongest constraint to date, excluding lifetimes shorter than [FORMULA OMISSION] at 90% CL for dark matter masses above [FORMULA OMISSION].</P>