@article{MarehnWilhelmPospisiletal.2019, author = {Marehn, David Thomas and Wilhelm, Detlef and Pospisil, Heike and Pizzoferrato, Roberto}, title = {Double entry method for the verification of data a chromatography data system receives}, series = {Journal of Sensors and Sensor Systems}, volume = {8}, journal = {Journal of Sensors and Sensor Systems}, issn = {2194-878X}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-12349}, pages = {207 -- 214}, year = {2019}, abstract = {The importance of software validation increases since the need for high usability and suitability of software applications grows. In order to reduce costs and manage risk factors, more and more recommendations and rules have been established. In the field of pharmacy the vendors of so-called chromatography data systems (CDSs) had to implement the guidelines of the Code of Federal Regulations Title 21 (CFR 21) during the last few years in order to fulfill the increasing requirements. The CFR 21 part 11 deals with electronic records and signatures. This part is binding for each company in the regulated environment that wishes to create, edit and sign electronic information instead of printing them on paper. Subsection CFR 21 part 11.10(h) explains how to perform an input check for manual user entries as well as for data that will be collected from an external device. In this article we present an approach performing the double entry method on data provided by the hardware instrument in order to investigate possible influences on the raw data by the handling CDS. A software tool has been written which allows us to communicate with a high-performance liquid chromatography (HPLC) detector and acquire data from it. The communication is completely independent of a CDS which is started separately and connected to the same system. Using this configuration we made a parallel data acquisition of two instances at the same time possible. Two CDSs have been tested and for at least one of them it has been shown that a comparison of the acquired data can be done as with the double entry method for the data verification. For the second CDS we checked whether it would be applicable after a few modifications. The given approach could be either used for a live data verification of produced raw data or as a single test during a software operational qualification to verify the data acquisition functionality of the software.}, language = {en} } @misc{SchaeferJetschniWangetal.2019, author = {Sch{\"a}fer, Marco and Jetschni, Christian and Wang, Chong and Pospisil, Heike}, title = {Optimierung des Rekonstruktions-Tools TSNI f{\"u}r genregulatorische Netzwerke mittels Parallelisierung und ein Vergleich mit Time Delay ARACNE}, series = {Wissenschaftliche Beitr{\"a}ge 2019}, volume = {23}, journal = {Wissenschaftliche Beitr{\"a}ge 2019}, issn = {0949-8214}, doi = {10.15771/0949-8214_2019_1}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-10767}, pages = {7 -- 10}, year = {2019}, abstract = {Gegenstand dieser Ver{\"o}fffentlichung ist eine Reimplementierung des TSNI (Time Series Network Identification)-Tools zur Rekonstruktion von genregulatorischen Netzwerken aus Zeitserien von Gen-Expressionsprofilen. Das auf gew{\"o}hnlichen Differentialgleichungen basierende Tool wurde algorithmisch verbessert und an die Verarbeitung großer Datens{\"a}tze angepasst. Durch Aussch{\"o}pfung des Potentials moderner Multi-CPU und GPU-Architekturen wurden die erforderlichen Berechnungen erheblich beschleunigt. Bei der {\"U}berf{\"u}hrung des mit Matlab implementierten Tools in die Programmiersprache C wurde zudem die ­Bedienbarkeit verbessert. Durch Einsatz der GPU-beschleunigten Mathematik-Bibliothek MAGMA konnten unter Verwendung eines normalen Desktop-Rechners Leistungssteigerungen um das 18,7-fache bei 11.000 Genen verzeichnet werden. Dar{\"u}ber hinaus rekonstruierte das verbesserte TSNI weitaus mehr biologisch richtige Beziehungen als vergleichbare Anwendungen.}, language = {de} } @article{KagelFrohmeGloekler2019, author = {Kagel, Heike and Frohme, Marcus and Gl{\"o}kler, J{\"o}rn}, title = {Photoacids in biochemical applications}, series = {Journal of Cellular Biotechnology}, volume = {4}, journal = {Journal of Cellular Biotechnology}, number = {1-2}, publisher = {IOS Press}, issn = {2352-3697}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-16123}, pages = {23 -- 30}, year = {2019}, abstract = {BACKGROUND: After excitation with light photoacids can change the pH in a solution by release of a proton. They have been used mostly for excited state proton transfer studies. In this review the general functionality and mechanisms and the subdivision of photoacids is explained. STATE OF THE ART: Different uses of photoacids are described, covering a wide range of various biochemical topics, focusing on biochemical applications. Examples for the introduced subdivisions are covered. CONCLUSIONS AND OUTLOOK: The areas in which photoacids can be employed are diverse. Photoacids have a promising future in biotechnology and biochemistry and should be considered for upcoming applications, especially in non-invasive control of biochemical reactions.}, language = {en} } @inproceedings{PulwerFiebelkornZeschetal.2019, author = {Pulwer, Silvio and Fiebelkorn, Richard and Zesch, Christoph and Steglich, Patrick and Villringer, Claus and Villasmunta, Francesco and Gedat, Egbert and Handrich, Jan and Schrader, Sigurd and Vandenhouten, Ralf}, title = {Endoscopic orientation by multimodal data fusion}, series = {Proc. SPIE 10931, MOEMS and Miniaturized Systems XVIII}, booktitle = {Proc. SPIE 10931, MOEMS and Miniaturized Systems XVIII}, issn = {1996-756X}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-11420}, year = {2019}, abstract = {To improve the feasibility of endoscopic inspection processes we developed a system that provides online information about position, orientation and viewing direction of endoscopes, to support the analysis of endoscopic images and to ease the operational handling of the equipment. The setup is based on an industrial endoscope consisting of a camera, various MEMS and multimodal data fusion. The software contains algorithms for feature and geometric structure recognition as well as Kalman filters. To track the distal end of the endoscope and to generate 3D point cloud data in real time the optical and photometrical characteristics of the system are registered and the movement of the endoscope is reconstructed by using image processing techniques.}, language = {en} } @inproceedings{ZeschSchraderProspositoetal.2019, author = {Zesch, Christoph and Schrader, Sigurd and Prosposito, Paolo and Lux, Oliver and Eichler, Hans J.}, title = {Raman lasers for trace gas detection}, publisher = {SPIE}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-15351}, pages = {114 -- 119}, year = {2019}, abstract = {The emission of commercial solid-state lasers is shifted by Raman lasers to selected wavelengths suitable for trace gas detection. High power Raman lasers based on Ba(NO3)2, diamond and silicon detect CO2, O3 and H2O. Raman lasers base on the physical effect of stimulated Raman scattering. Two new Raman crystals (Spodumene and LuAlO3) are investigated and their SRS-spectra is shown.}, language = {en} } @article{BauerFursenkoMarschmeyeretal.2019, author = {Bauer, Joachim and Fursenko, Oksana and Marschmeyer, Steffen and Heinrich, Friedhelm and Villasmunta, Francesco and Villringer, Claus and Zesch, Christoph and Schrader, Sigurd}, title = {Spectroscopic reflectometry for characterization of Through Silicon Via profile of Bosch etching process}, series = {Journal of Vacuum Science \& Technology B}, volume = {37}, journal = {Journal of Vacuum Science \& Technology B}, number = {6}, publisher = {American Vacuum Society (AVS)}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-16093}, year = {2019}, abstract = {Through Silicon Via (TSV) technology is a key in 3D integration of circuits by the creation of interconnects using vias, which go through the full silicon wafer. Typically, a highly-selective Bosch Si etch process is used. It is characterized by a high etch rate at a high aspect ratio, whereby scallops on the sidewalls are generated. In this work, square via arrays with dimensions from 3 to 50 μm and up to 300 μm depth were fabricated and analyzed by spectroscopic reflectometry. The reflectometric data are compared to simulations by a novel theoretical approach. In order to simulate the reflectance spectra of TSV arrays, a combination of 2D and 3D rigorous coupled wave analysis was applied. Besides the via depth, the sidewall angle and the corner radius of the bottom profile were considered in the model. The general requirements on spectral resolution in TSV metrology are discussed.}, language = {en} } @misc{HartmannTataiKaiseretal.2019, author = {Hartmann, Lutz and Tatai, Tiberiu-Mihai and Kaiser, Mario and Dreyer, Christian}, title = {Erw{\"a}rmung von Materialien und Werkstoffen durch Anwendung von Mikrowellentechnologien}, series = {Wissenschaftliche Beitr{\"a}ge 2019}, volume = {23}, journal = {Wissenschaftliche Beitr{\"a}ge 2019}, issn = {0949-8214}, doi = {10.15771/0949-8214_2019_6}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-10812}, pages = {39 -- 48}, year = {2019}, abstract = {Die Erw{\"a}rmung unterschiedlicher Materialien im ­Kontext verschiedener Anwendungen kann anhand der Bestrahlung mit Mikrowellen in geeignet konstruierten {\"O}fen erfolgen. Der vorliegende Beitrag beginnt mit einer Vorstellung der mikroskopischen Mechanismen der Erw{\"a}rmung von Materie mittels Mikrowellen sowie einem Abriss ihrer theoretischen Beschreibung. Im Folgenden werden die breitbandige dielektrische Spektroskopie und die Simulation elektromagnetischer Felder als Hilfsmittel eingef{\"u}hrt, die Effizienz des mikrowellenbasierten Heizens f{\"u}r bestimmte Materialien vorab einsch{\"a}tzen zu k{\"o}nnen. Nach der Vorstellung zweier unterschiedlicher Mikrowellenanlagen, namentlich eines Kammer- und eines Durchlaufmikrowellenofens, wird die thermische Behandlung unterschiedlicher Materialien mittels Mikrowellen an drei Beispielen illustriert.}, language = {de} } @misc{HotesSchwahnFabienke2019, author = {Hotes, Andreas G. and Schwahn, Klaus-J{\"u}rgen and Fabienke, Henrike}, title = {Betrachtung von neuartigen Antriebs- und Kraftstoffkonzepten mit dem Ziel der Konzeption ­einer Hybridtankstelle f{\"u}r den Flugplatz Sch{\"o}nhagen f{\"u}r die Versorgung von Luftfahrzeugen mit nachhaltigen Kraftstoffen}, series = {Wissenschaftliche Beitr{\"a}ge 2019}, volume = {23}, journal = {Wissenschaftliche Beitr{\"a}ge 2019}, issn = {0949-8214}, doi = {10.15771/0949-8214_2019_7}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-11939}, pages = {49 -- 55}, year = {2019}, abstract = {Dieser wissenschaftliche Beitrag befasst sich zun{\"a}chst mit der Betrachtung von neuartigen und nachhaltigen Antriebs- und Kraftstoffkonzepten f{\"u}r den Einsatz in der Luftfahrt, die zum Erreichen der hochgesteckten Klimaschutzziele auf nationaler, europ{\"a}ischer und internationaler Ebene beitragen sollen. Um die Energieversorgung dieser Luftfahrzeuge gew{\"a}hrleisten zu k{\"o}nnen, wurde ein Tankstellensystem beispielhaft f{\"u}r den Flugplatz Sch{\"o}nhagen konzipiert, welches Strom, Wasserstoff und Power-to-Liquid-Kraftstoff f{\"u}r Elektro-, Wasserstoff- und Luftfahrzeuge mit konventionellem Verbrennungsmotor sowie f{\"u}r Hybridflugzeuge zur Verf{\"u}gung stellen soll. Ziel dieses Konzeptes ist die komplette Eigenproduktion der Kraftstoffe auf dem Flugplatz. Hierzu wurden rechtliche, wirtschaftliche und vor allem technische Voraussetzungen untersucht und ausgewertet sowie Berechnungen bez{\"u}glich der ben{\"o}tigten Kraftstoff- und Stromkapazit{\"a}ten durchgef{\"u}hrt.}, language = {de} } @misc{GerhardLetienCressentetal.2019, author = {Gerhard, Christoph and Letien, Emilie and Cressent, Thomas and Hofmann, Mandy}, title = {Impact of the plasma power on plasma-induced increase in absorption of fused silica}, series = {Wissenschaftliche Beitr{\"a}ge 2019}, volume = {23}, journal = {Wissenschaftliche Beitr{\"a}ge 2019}, issn = {0949-8214}, doi = {10.15771/0949-8214_2019_5}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-10802}, pages = {33 -- 37}, year = {2019}, abstract = {In the last decades, laser machining of fused silica has gained in importance where the main challenge is to overcome the high transmission of this medium in order to achieve surface absorption. One approach is plasma treatment using hydrogenous process gases. In doing so, a near-surface glass layer is chemically modified by a removal of oxygen and an implantation of hydrogen, resulting in the formation of optically active defects and an increase in absorption. Against this background, the impact of the plasma power on plasma-induced increase in absorption of fused silica was investigated in the present work. Here, the highest efficiency of the plasma treatment process was found at the lowest applied plasma power whereas for higher plasma powers, a notably lower increase in absorption was observed. This effect is attributed to the decomposition of plasma species required for initiating the formation of optically active defects within the glass. Such decomposition increases with rising power due to the corresponding increase in electric field strength within the plasma. This finding is of substantial interest for an extensive understanding of plasma-glass interactions.}, language = {en} } @misc{HandrichVandenhouten2019, author = {Handrich, Jan and Vandenhouten, Ralf}, title = {Erweiterung eines landmarkenbasierten Innenraumortungsverfahrens f{\"u}r Mobilger{\"a}te mit ARCore}, series = {Wissenschaftliche Beitr{\"a}ge 2019}, volume = {23}, journal = {Wissenschaftliche Beitr{\"a}ge 2019}, issn = {0949-8214}, doi = {10.15771/0949-8214_2019_4}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-10790}, pages = {27 -- 32}, year = {2019}, abstract = {Die Lokalisierung in Innenr{\"a}umen, die sich nicht auf Satellitennavigation wie GPS verlassen kann, ist nach wie vor eine Herausforderung. Viele Methoden zur Lokalisierung in Innenr{\"a}umen beruhen auf Funksignalen oder anderen Sendern (z.B. Infrarot), die eine kostenintensive Infrastruktur erfordern, die in einem Geb{\"a}ude installiert werden muss. Außerdem sind diese Techniken ungenau, wenn Reflexionen der Signale in einem Geb{\"a}ude auftreten. Die Forschungsgruppe Telematik der TH Wildau hat f{\"u}r diese Problemstellung ein optisches Verfahren zur Innenraumlokalisierung entwickelt, das die Kamera eines mobilen Ger{\"a}ts verwendet. Dieser Ansatz erfordert nur die Verf{\"u}gbarkeit von mehreren identifizierbaren Landmarken, die kosteng{\"u}nstig in einem Geb{\"a}ude installiert werden k{\"o}nnen. In diesem Beitrag soll eine M{\"o}glichkeit vorgestellt werden, dieses landmarkenbasierte Verfahren mit der Augmented Reality-Bibliothek ARCore von Google zu erweitern, um eine kontinuierliche Positionsermittlung zu erm{\"o}glichen, auch wenn vor{\"u}bergehend keine Landmarken durch die Ger{\"a}tekamera erfasst ­werden k{\"o}nnen.}, language = {de} } @misc{SchwahnAngermannRuetherKindel2019, author = {Schwahn, Cheryl Nicoletta and Angermann, Sven and R{\"u}ther-Kindel, Wolfgang}, title = {Untersuchungen zu Mensch-Maschine-Schnittstellen eines Pilotenassistenzsystems zur Begegnung potentieller Gefahrensituationen der Allgemeinen Luftfahrt}, series = {Wissenschaftliche Beitr{\"a}ge 2019}, volume = {23}, journal = {Wissenschaftliche Beitr{\"a}ge 2019}, issn = {0949-8214}, doi = {10.15771/0949-8214_2019_8}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-11940}, pages = {57 -- 62}, year = {2019}, abstract = {Privatpiloten, die sich in der Allgemeinen Luftfahrt bewegen, sind h{\"a}ufig anderen Gefahren ausgesetzt, als Piloten großer Verkehrsflugzeuge. Gefahrensituationen bringen Piloten schnell an Wissensl{\"u}cken und Kapazit{\"a}tsgrenzen. F{\"u}r Privatpiloten stellt dabei der Kontrollverlust im Flug die h{\"a}ufigste Unfallursache dar. Das Forschungsvorhaben Virtual Instructor for General Aviation (VIGA) des Fachgebiets Luftfahrttechnik leistet einen wesentlichen Beitrag zur Vermeidung dieser Unf{\"a}lle. Ziel des Vorhabens ist es, ein Assistenzsystem zu entwickeln, das Privatpiloten fr{\"u}hzeitig mit Handlungsempfehlungen unterst{\"u}tzt, sobald diese in eine unkontrollierte Fluglage gelangen. Dieser wissenschaftliche Beitrag stellt die Grundlagen des Forschungsvorhabens VIGA dar und beschreibt eine Konzepterstellung zur Mensch-Maschine-Schnittstelle von Assistenzsystemen der zivilen Luftfahrt unter Betrachtung der psychologischen Belastung in Notsituationen. Belastungssituationen beeintr{\"a}chtigen sowohl die Wahrnehmung der Piloten, beispielsweise durch selektive Taubheit oder optische T{\"a}uschungen als auch die variierende Reaktionszeit des Piloten auf verschiedene Reize. Ziel ist es, eine geeignete Mensch-Maschine-Schnittstelle zu entwickeln, die jederzeit die Aufmerksamkeit des Piloten erlangt und Handlungsempfehlungen zielgerecht an diesen ausgibt. Erkenntnisse aus diesem Beitrag finden direkte Anwendung im Vorhaben VIGA.}, language = {de} } @misc{OeckelHeimannAngermannetal.2019, author = {Oeckel, Konrad and Heimann, Jan and Angermann, Sven and Kerscher, Michael and Frahm, Andreas and Heilmann, Gunnar and R{\"u}ther-Kindel, Wolfgang}, title = {Vergleichende akustische Untersuchung von Drohnen-Propellern}, series = {Wissenschaftliche Beitr{\"a}ge 2019}, volume = {23}, journal = {Wissenschaftliche Beitr{\"a}ge 2019}, issn = {0949-8214}, doi = {10.15771/0949-8214_2019_9}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-11957}, pages = {63 -- 69}, year = {2019}, abstract = {Die Reduzierung von Flugl{\"a}rm ist eine der wesentlichen Herausforderungen der Luftfahrtindustrie. Dies betrifft ebenso unbemannte Luftfahrtsysteme, die zuk{\"u}nftig eine signifikante Rolle im allt{\"a}glichen Leben spielen werden. In diesem Zusammenhang wurde im Fachgebiet Luftfahrttechnik der TH Wildau das energetische Potential von Winglets an Propellern („Proplets") untersucht, deren Einsatz sowohl eine Verbesserung der aerodynamischen Effizienz als auch eine Minderung der Ger{\"a}uschemission versprachen. Daher musste der akustische Einfluss dieser Proplets pr{\"a}zise bestimmt werden. In diesem Beitrag wird erstmals die Ger{\"a}uschemission eines mit Proplets ausger{\"u}steten Propellers mit einem Referenzpropeller verglichen. Beide Pr{\"u}fst{\"u}cke sind, abgesehen von den Blattspitzen, identisch. Neben normgerechten, herk{\"o}mmlichen Messungen der Schallleistungspegel sowie psychoakustischer Eigenschaften werden beide Pr{\"u}fst{\"u}cke mit einem Mikrofon-Array („Akustische Kamera") untersucht, um die L{\"a}rmquellen entlang der Propellerbl{\"a}tter zu visualisieren. Hierf{\"u}r wird erstmals ein virtuell mitrotierendes Array angewendet, um die aero-akustischen Quellen am stehenden Blatt zu identifizieren.}, language = {de} } @misc{RiedelSchaeferParaketal.2019, author = {Riedel, Marc and Sch{\"a}fer, Daniel and Parak, Wolfgang J. and Ruff, Adrian and Schuhmann, Wolfgang and Lisdat, Fred}, title = {Quantum Dot-modifizierte TiO2-Strukturen f{\"u}r die Licht-gesteuerte Bioelektrokatalyse}, series = {Wissenschaftliche Beitr{\"a}ge 2019}, volume = {23}, journal = {Wissenschaftliche Beitr{\"a}ge 2019}, issn = {0949-8214}, doi = {10.15771/0949-8214_2019_2}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-10773}, pages = {11 -- 17}, year = {2019}, abstract = {Die funktionale Kopplung von photoaktiven Nanostrukturen mit Enzymen stellt eine neue Strategie zum Aufbau lichtgesteuerter biohybrider Systeme dar. Hier sind Untersuchungen zusammengefasst, welche die effiziente Kontaktierung der FAD-abh{\"a}ngigen Glukosedehydrogenase (FAD-GDH) mit Hilfe eines Osmium-Redoxpolymers (P Os ) an PbS-Quantum Dots (PbS QDs) zeigen, welche direkt auf dreidimensionalen TiO 2 -Elektrodenstrukturen synthetisiert wurden. Diese biohybriden Strukturen erlauben die Licht-induzierte Oxidation von Glukose. Dazu wird zun{\"a}chst ein Verfahren vorgestellt, bei welchem durch den Aufbau invers-opaler TiO 2 (IO-TiO 2 ) Strukturen hohe Bindungskapazit{\"a}ten f{\"u}r die Integration von QDs, Redoxpolymer und Enzym erreicht werden. In Folge wird gezeigt wie elektrochemische Signalketten durch Licht gesteuert werden k{\"o}nnen, indem Ladungstr{\"a}ger in den QDs unter Beleuchtung erzeugt werden. Diese Aktivierung erm{\"o}glicht dann die Ausbildung einer Elektrontransferkaskade vom Enzym {\"u}ber das Redoxpolymer zu den QDs und final zur IO-TiO 2 -Elektrode. Die resultierenden anodischen Photostr{\"o}me k{\"o}nnen durch das Potential, die Lichtintensit{\"a}t und die Glukosekonzentration moduliert werden. So k{\"o}nnen in Anwesenheit von Glukose Photostr{\"o}me von bis zu 207 μA/cm2 und erste Oxidationssignale bereits bei einem Potential von -540 mV vs Ag/AgCl, 1 M KCl erhalten werden. Dies entspricht einem Potentialgewinn von {\"u}ber 500 mV im Vergleich zu nicht lichtsensitiven Elektroden. Das vorgestellte biohybride System kombiniert Vorteile einer großen Oberfl{\"a}che (durch IO-TiO 2 -Struktur), die effiziente Ladungstr{\"a}gergenerierung und -trennung an der QD/TiO 2 -Schnittstelle sowie die effiziente Kontaktierung von FAD-GDH mit den QDs mit Hilfe eines Redoxpolymers. Die Ergebnisse verdeutlichen das Potential dieser leistungsf{\"a}higen Photobioanode f{\"u}r die Sensorik und die Erzeugung von Energie aus Licht und Glukose.}, language = {de} } @inproceedings{AlarconSchneiderKamenzkyetal.2019, author = {Alarc{\´o}n, Daniel and Schneider, Sarah and Kamenzky, Robert and Blaschke, Peter}, title = {Across the Picket Fence: Influence of Sampling Frequency in Automatic Impact Modal Testing}, series = {Special Topics in Structural Dynamics, Volume 5 : Proceedings of the 36th IMAC, A Conference and Exposition on Structural Dynamics 2018}, booktitle = {Special Topics in Structural Dynamics, Volume 5 : Proceedings of the 36th IMAC, A Conference and Exposition on Structural Dynamics 2018}, publisher = {River Publishers}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-21515}, year = {2019}, abstract = {Automatic impact modal testing is a technique gaining momentum in recent years thanks to the popularization of Scanning Laser Doppler Vibrometry. These systems allow automatizing the output measurement of thousands of degrees of freedom in a short time. The use of automatic impact modal hammers allows automatizing the excitation input and broadband excitation without loading a structure with an extra mass or other drawbacks. However, the impact force repeatability is a prominent concern among test engineers, especially those who work with materials with non-proportional force/response ratios. Assessing the impact force repeatability of a given automatic modal hammer or test rig is necessary in order to ensure the right response level is measured impact after impact. The assessment procedure can be misleading if not done right. Studying the automatic modal hammer repeatability under typical modal test conditions invariably leads to impact signals strongly distorted by the so called picket fence effect. This results in impacts sampled by only 3-4 data points; insufficient to accurately describe the actual impact force signals and the short contact times between hammer tip and structure. In the reality, the impacts are of larger magnitudes and shorter contact times than what is shown by the analyzer in typical test conditions. This work studies the influence of the sampling frequency and the test structures used on the repeatability assessment of automatic impact modal hammers. Impact force signals are acquired in this work with enough resolution to eliminate the picket fence effect and truly evaluate how repeatable and reproducible automatic impacts are. The practicality of the procedure, which involves very large datasets and long testing times, is discussed. Guidelines are offered at the end of the paper for a successful repeatability and reproducibility assessment of automatic impact modal hammers.}, language = {en} } @inproceedings{SchneiderMallareddyAlarconetal.2019, author = {Schneider, Sarah and Mallareddy, Tarun Teja and Alarc{\´o}n, Daniel and Kamenzky, Robert and Blaschke, Peter}, title = {Experimental Modal Analysis of Structures with Conventional Versus Contact-Free Suspension}, series = {Special Topics in Structural Dynamics, Volume 5 : Proceedings of the 36th IMAC, A Conference and Exposition on Structural Dynamics 2018}, booktitle = {Special Topics in Structural Dynamics, Volume 5 : Proceedings of the 36th IMAC, A Conference and Exposition on Structural Dynamics 2018}, publisher = {River Publishers}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-21533}, year = {2019}, abstract = {The existence of free boundary conditions is frequently assumed for Experimental Modal Analysis (EMA) of a structure. However, free-free conditions can only be approximated because the structure must be supported in some manner. Therefore, comparing simulated data with experimental data can be deceiving, because these suspensions falsify modal parameters especially structural damping and stiffness. The current scenario of structural analysis is more towards focusing on modal updating or correlation, rather than the simulation results (FE) or the experimental results. So it is imperative to bridge the gap between FE and EMA, by carefully studying various parameters. To overcome these drawbacks, levitation is suggested as a truly free-free suspension method. The levitation method was developed to allow a non-destructive, adaptable, and completely contactless approach for material testing: the structure under test is suspended on a thin film of pressurized air providing an aerodynamic bearing, levitating the specimen. Two suspension devices were constructed. Pressurized air is circulated into a casing with a single outlet ("air cushion") or a fine grid of outlets ("air bed"). A study was performed to investigate the influence of the support conditions on the modal parameters eigenfrequency and damping. Tested specimens were a brass plate, a stainless steel plate and two composite material probes. The tested suspension methods were (a) foam mat, (b) air cushion and (c) air bed. Modal tests were performed using a Scanning Laser Doppler Vibrometer (SLDV) and an automatic modal hammer for excitation. Evaluations of the measurements were performed manually. The results showed that the detected eigenfrequencies of the metallic specimen have a variation below ±0.3\% for the tested suspension methods. This variation is 10 times higher for the composite plates and lies between ±3\%. The damping ratios of the levitation suspensions show the different material behavior of metallic and composite specimen: damping ratios of metallic specimen lie between 0.05-0.5\% whereas damping ratios of composite plates are ten times higher and lie between 0.3\% and 3\%. The damping ratios measured with the air cushion are smaller than the damping ratios for the air bed supporting the hypothesis that a laminar air film under the specimen leads to less additional damping. The study shows that EMA can be performed on metallic and composite specimens using contact-less suspension methods. Especially for light-weight material specimens where EMA cannot be performed or where the results are not reliable, the contact-less suspension (levitation method) can be used.}, language = {en} } @inproceedings{MallareddyAlarconSchneideretal.2019, author = {Mallareddy, Tarun Teja and Alarc{\´o}n, Daniel and Schneider, Sarah and Blaschke, Peter}, title = {The Influence of Geometrical Correlation in Modal Validation Using Automated 3D Metrology}, series = {Rotating Machinery, Vibro-Acoustics \& Laser Vibrometry, Volume 7 : Proceedings of the 36th IMAC, A Conference and Exposition on Structural Dynamics 2018}, booktitle = {Rotating Machinery, Vibro-Acoustics \& Laser Vibrometry, Volume 7 : Proceedings of the 36th IMAC, A Conference and Exposition on Structural Dynamics 2018}, publisher = {River Publishers}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-21524}, year = {2019}, abstract = {Structural analysis is a major part of all manufacturing and testing industries. The need for high level accuracy of the results in the testing field has increased progressively, resulting in development of advanced state of art techniques. In order to acquire the vibrational characteristics of a structure, a detailed Finite Element Analysis (FEA) modelling is performed. Also, Experimental Modal Analysis (EMA) is conducted to extract the dynamic characteristics of a structure. The results obtained from both the processes are correlated for validation purposes. Based on the correlation (good or bad) the structural analysis is validated. In most cases the correlation is not satisfactory; it is mainly because of the boundary conditions that differ in FE and EMA. This research study explains in detail how important the boundary conditions are for modal validation. But the most imperative part, as the first step of correlation, is the geometry analysis. If the geometrical correlation is not accurate, the later part of correlation will turn out to be an assumption based on inaccuracies. Assumption of a geometrical correlation, without being sure of the differences, will lead to inaccurate results for validation. A reference plate is tested and simulated by using EMA and FEA techniques respectively. EMA is conducted by using a 3D SLDV for measuring the output response and the input force of excitation is induced by a Scalable Automatic Modal hammer (SAM). This plate is then scanned using ATOS Triple Scan II GOM 3D geometry scanner. The scanned results are compared with the FE model of the reference plate. The results presented show the importance of geometrical correlation for modal validation and provide results of deviations that were observed on a reference plate. With these conclusions, working on modal validation can be developed by reducing the inaccuracies for the presentation of correlation.}, language = {en} } @inproceedings{MallareddySchneiderBlaschke2019, author = {Mallareddy, Tarun Teja and Schneider, Sarah and Blaschke, Peter}, title = {Advanced Hammer Excitation Technique for Impact Modal Testing on Lightweight Materials Using Scalable Automatic Modal Hammer}, series = {Topics in Modal Analysis \& Testing, Volume 9 : Proceedings of the 36th IMAC, A Conference and Exposition on Structural Dynamics 2018}, booktitle = {Topics in Modal Analysis \& Testing, Volume 9 : Proceedings of the 36th IMAC, A Conference and Exposition on Structural Dynamics 2018}, publisher = {River Publishers}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-21508}, year = {2019}, abstract = {Experimental Modal Analysis (EMA) on a lightweight material has proven to be very challenging in the recent past. The applications of these materials have increased invariably in various fields and so have a high demand for Research \& Development (R\&D). A lightweight material is very sensitive in terms of vibration. EMA on these materials in free - free boundary condition is very complicated as the hammer excitation becomes very difficult. In order to acquire valid results, the conditions are modified, and in consequence, obtain inaccurate dynamic characteristics. Some of the major challenges faced are: (a) material getting displaced from its original position after every hit, (b) difficulties in obtaining a single hit, (c) reproducing the same excitation force level for averaging output response. Overcoming these crucial challenges can result in reducing the inaccuracies in the results. Scalable Automatic Modal hammer (SAM) is developed to overcome these challenges and enables the ability to reproduce the same force level of excitation. This advanced hammer excitation technique has the capability to avoid the double hit, adjust the repeatability of force level and automatizes the entire excitation process. In this research paper, a light weight material is experimented under free-free boundary condition and the obtained results are analyzed. The input hammer excitation is provided by SAM and the output contactless response is measured by Scanning Laser Doppler Vibrometer (SLDV). The conclusions provided will reflect the importance of repeatability and reproducibility of hammer excitation force level in order to acquire accurate results. The controlling of SAM, by changing various parameters, in order to precisely excite lightweight structures will be demonstrated.}, language = {en} }