TY  - JOUR
A1  - Meyer, Max-Arno
A1  - Granrath, Christian
A1  - Feyerl, Günter
A1  - Richenhagen, Johannes
A1  - Kaths, Jakob
A1  - Andert, Jakob
T1  - Closed-loop platoon simulation with cooperative intelligent transportation systems based on vehicle-to-X communication
JF  - Simulation Modelling Practice and Theory
Y1  - 2021
U6  - https://doi.org/10.1016/j.simpat.2020.102173
SN  - 1569-190X
VL  - 106
IS  - Art. 102173
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Mikucki, Jill Ann
A1  - Schuler, C. G.
A1  - Digel, Ilya
A1  - Kowalski, Julia
A1  - Tuttle, M. J.
A1  - Chua, Michelle
A1  - Davis, R.
A1  - Purcell, Alicia
A1  - Ghosh, D.
A1  - Francke, G.
A1  - Feldmann, M.
A1  - Espe, C.
A1  - Heinen, Dirk
A1  - Dachwald, Bernd
A1  - Clemens, Joachim
A1  - Lyons, W. B.
A1  - Tulaczyk, S.
T1  - Field-Based planetary protection operations for melt probes: validation of clean access into the blood falls, antarctica, englacial ecosystem
JF  - Astrobiology
N2  - Subglacial environments on Earth offer important analogs to Ocean World targets in our solar system. These unique microbial ecosystems remain understudied due to the challenges of access through thick glacial ice (tens to hundreds of meters). Additionally, sub-ice collections must be conducted in a clean manner to ensure sample integrity for downstream microbiological and geochemical analyses. We describe the field-based cleaning of a melt probe that was used to collect brine samples from within a glacier conduit at Blood Falls, Antarctica, for geomicrobiological studies. We used a thermoelectric melting probe called the IceMole that was designed to be minimally invasive in that the logistical requirements in support of drilling operations were small and the probe could be cleaned, even in a remote field setting, so as to minimize potential contamination. In our study, the exterior bioburden on the IceMole was reduced to levels measured in most clean rooms, and below that of the ice surrounding our sampling target. Potential microbial contaminants were identified during the cleaning process; however, very few were detected in the final englacial sample collected with the IceMole and were present in extremely low abundances (∼0.063% of 16S rRNA gene amplicon sequences). This cleaning protocol can help minimize contamination when working in remote field locations, support microbiological sampling of terrestrial subglacial environments using melting probes, and help inform planetary protection challenges for Ocean World analog mission concepts.
Y1  - 2023
U6  - https://doi.org/10.1089/ast.2021.0102
SN  - 1557-8070 (online)
SN  - 153-1074 (print)
VL  - 23
IS  - 11
SP  - 1165
EP  - 1178
PB  - Liebert
CY  - New York, NY
ER  - 
TY  - CHAP
A1  - Mulsow, Niklas A.
A1  - Hülsen, Benjamin
A1  - Gützlaff, Joel
A1  - Spies, Leon
A1  - Bresser, Andreas
A1  - Dabrowski, Adam
A1  - Czupalla, Markus
A1  - Kirchner, Frank
T1  - Concept and design of an autonomous micro rover for long term lunar exploration
T2  - Proceedings of the 74th International Astronautical Congress
N2  - Research on robotic lunar exploration has seen a broad revival, especially since the Google Lunar X-Prize increasingly brought private endeavors into play. This development is supported by national agencies with the aim of enabling long-term lunar infrastructure for in-situ operations and the establishment of a moon village. One challenge for effective exploration missions is developing a compact and lightweight robotic rover to reduce launch costs and open the possibility for secondary payload options. Existing micro rovers for exploration missions are clearly limited by their design for one day of sunlight and their low level of autonomy. For expanding the potential mission applications and range of use, an extension of lifetime could be reached by surviving the lunar night and providing a higher level of autonomy. To address this objective, the paper presents a system design concept for a lightweight micro rover with long-term mission duration capabilities, derived from a multi-day lunar mission scenario at equatorial regions. Technical solution approaches are described, analyzed, and evaluated, with emphasis put on the harmonization of hardware selection due to a strictly limited budget in dimensions and power.
Y1  - 2023
N1  - 74. International Astronautical Congress (IAC-2023), October 2-6 2023, Baku, Azerbaijan
PB  - dfki
CY  - Saarbrücken
ER  - 
TY  - CHAP
A1  - Möhren, Felix
A1  - Bergmann, Ole
A1  - Janser, Frank
A1  - Braun, Carsten
T1  - On the determination of harmonic propeller loads
T2  - AIAA SCITECH 2023 Forum
N2  - Dynamic loads significantly impact the structural design of propeller blades due to fatigue and static strength. Since propellers are elastic structures, deformations and aerodynamic loads are coupled. In the past, propeller manufacturers established procedures to determine unsteady aerodynamic loads and the structural response with analytical steady-state calculations. According to the approach, aeroelastic coupling primarily consists of torsional deformations. They neglect bending deformations, deformation velocities, and inertia terms. This paper validates the assumptions above for a General Aviation propeller and a lift propeller for urban air mobility or large cargo drones. Fully coupled reduced-order simulations determine the dynamic loads in the time domain. A quasi-steady blade element momentum approach transfers loads to one-dimensional finite beam elements. The simulation results are in relatively good agreement with the analytical method for the General Aviation propeller but show increasing errors for the slender lift propeller. The analytical approach is modified to consider the induced velocities. Still, inertia and velocity proportional terms play a significant role for the lift propeller due to increased elasticity. The assumption that only torsional deformations significantly impact the dynamic loads of propellers is not valid. Adequate determination of dynamic loads of such designs requires coupled aeroelastic simulations or advanced analytical procedures.
Y1  - 2023
U6  - https://doi.org/10.2514/6.2023-2404
N1  - AIAA SCITECH 2023 Forum, 23-27 January 2023, National Harbor, Md & Online
PB  - AIAA
ER  - 
TY  - JOUR
A1  - Neu, Eugen
A1  - Janser, Frank
A1  - Khatibi, Akbar A.
A1  - Braun, Carsten
A1  - Orifici, Adrian C.
T1  - Operational Modal Analysis of a wing excited by transonic flow
JF  - Aerospace Science and Technology
N2  - Operational Modal Analysis (OMA) is a promising candidate for flutter testing and Structural Health Monitoring (SHM) of aircraft wings that are passively excited by wind loads. However, no studies have been published where OMA is tested in transonic flows, which is the dominant condition for large civil aircraft and is characterized by complex and unique aerodynamic phenomena. We use data from the HIRENASD large-scale wind tunnel experiment to automatically extract modal parameters from an ambiently excited wing operated in the transonic regime using two OMA methods: Stochastic Subspace Identification (SSI) and Frequency Domain Decomposition (FDD). The system response is evaluated based on accelerometer measurements. The excitation is investigated from surface pressure measurements. The forcing function is shown to be non-white, non-stationary and contaminated by narrow-banded transonic disturbances. All these properties violate fundamental OMA assumptions about the forcing function. Despite this, all physical modes in the investigated frequency range were successfully identified, and in addition transonic pressure waves were identified as physical modes as well. The SSI method showed superior identification capabilities for the investigated case. The investigation shows that complex transonic flows can interfere with OMA. This can make existing approaches for modal tracking unsuitable for their application to aircraft wings operated in the transonic flight regime. Approaches to separate the true physical modes from the transonic disturbances are discussed.
Y1  - 2016
U6  - https://doi.org/10.1016/j.ast.2015.11.032
SN  - 1270-9638
VL  - 49
SP  - 73
EP  - 79
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - CHAP
A1  - Neu, Eugen
A1  - Janser, Frank
A1  - Khatibi, Akbar A.
A1  - Orifici, Adrian C.
T1  - Operational modal analysis of a cantilever in a wind tunnel using optical fiber bragg grating sensors
T2  - 6th International Operational Modal Analysis Conference. IOMAC´15. 2015 May 12-14 Gijon - Spain
Y1  - 2015
U6  - https://doi.org/10.13140/RG.2.1.3753.0324
ER  - 
TY  - CHAP
A1  - Neu, Eugen
A1  - Janser, Frank
A1  - Khatibi, Akbar A.
A1  - Orifici, Adrian C.
T1  - In-flight vibration-based structural health monitoring of aircraft wings
T2  - 30th Congress of the internatonal council of the aeronautical sciences : 25.-30. September 2016, Daejeon, Korea
N2  - This work presents a methodology for automated
damage-sensitive feature extraction and anomaly
detection under multivariate operational variability
for in-flight assessment of wings. The
method uses a passive excitation approach, i. e.
without the need for artificial actuation. The
modal system properties (natural frequencies and
damping ratios) are used as damage-sensitive
features. Special emphasis is placed on the use
of Fiber Bragg Grating (FBG) sensing technology
and the consideration of Operational and
Environmental Variability (OEV). Measurements
from a wind tunnel investigation with a composite
cantilever equipped with FBG and piezoelectric
sensors are used to successfully detect an impact
damage. In addition, the feasibility of damage
localisation and severity estimation is evaluated
based on the coupling found between damageand
OEV-induced feature changes.
Y1  - 2016
ER  - 
TY  - JOUR
A1  - Neu, Eugen
A1  - Janser, Frank
A1  - Khatibi, Akbar A.
A1  - Orifici, Adrian C.
T1  - Fully Automated Operational Modal Analysis using multi-stage clustering
JF  - Mechanical Systems and Signal Processing
Y1  - 2017
U6  - https://doi.org/10.1016/j.ymssp.2016.07.031
SN  - 0888-3270
VL  - Vol. 84, Part A
SP  - 308
EP  - 323
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Neu, Eugen
A1  - Janser, Frank
A1  - Khatibi, Akbar A.
A1  - Orifici, Adrian C.
T1  - Automated modal parameter-based anomaly detection under varying wind excitation
JF  - Structural Health Monitoring
N2  - Wind-induced operational variability is one of the major challenges for structural health monitoring of slender engineering structures like aircraft wings or wind turbine blades. Damage sensitive features often show an even bigger sensitivity to operational variability. In this study a composite cantilever was subjected to multiple mass configurations, velocities and angles of attack in a controlled wind tunnel environment. A small-scale impact damage was introduced to the specimen and the structural response measurements were repeated. The proposed damage detection methodology is based on automated operational modal analysis. A novel baseline preparation procedure is described that reduces the amount of user interaction to the provision of a single consistency threshold. The procedure starts with an indeterminate number of operational modal analysis identifications from a large number of datasets and returns a complete baseline matrix of natural frequencies and damping ratios that is suitable for subsequent anomaly detection. Mahalanobis distance-based anomaly detection is then applied to successfully detect the damage under varying severities of operational variability and with various degrees of knowledge about the present operational conditions. The damage detection capabilities of the proposed methodology were found to be excellent under varying velocities and angles of attack. Damage detection was less successful under joint mass and wind variability but could be significantly improved through the provision of the currently encountered operational conditions.
Y1  - 2016
U6  - https://doi.org/10.1177/1475921716665803
SN  - 1475-9217
VL  - 15
IS  - 6
SP  - 1
EP  - 20
PB  - Sage
CY  - London
ER  - 
TY  - CHAP
A1  - Niedermeier, H.
A1  - Clemens, J.
A1  - Kowalski, Julia
A1  - Macht, S.
A1  - Heinen, D.
A1  - Hoffmann, R.
A1  - Linder, Peter
T1  - Navigation system for a research ice probe for antarctic glaciers
T2  - IEEE/ION Position, Location and Navigation Symposium (PLANS) ; 5-8 May 2014, Monterey, Calif.
Y1  - 2014
SN  - 978-1-4799-3319-8
SP  - 959
EP  - 975
PB  - IEEE
CY  - Piscataway, NJ
ER  -