TY  - JOUR
A1  - Fleischhaker, Robert
A1  - Evers, Jörg
A1  - Dey, Tarak N.
T1  - Phase modulation induced by cooperative effects in electromagnetically induced transparency
JF  - Physical Review A - Atomic, molecular, and optical physics
N2  - We analyze the influence of dipole-dipole interactions in an electromagnetically induced transparency set up for a density at the onset of cooperative effects. To this end, we include mean-field models for the influence of local-field corrections and radiation trapping into our calculation. We show both analytically and numerically that the polarization contribution to the local field strongly modulates the phase of a weak pulse. We give an intuitive explanation for this local-field-induced phase modulation and demonstrate that it distinctively differs from the nonlinear self-phase-modulation that a strong pulse experiences in a Kerr medium.
Y1  - 2010
U6  - https://doi.org/10.1103/PhysRevA.82.013815
SN  - 1050-2947
VL  - 82
IS  - 1
PB  - AIP Publishing
CY  - Melville, NY
ER  - 
TY  - JOUR
A1  - Hagemann, Hans-Jürgen
A1  - Bachmann, Peter K.
A1  - Lade, H.
A1  - Leers, D.
A1  - Wiechert, Detlef U.
A1  - Wilson, H.
A1  - Fournier, D.
A1  - Plamann, Karsten
T1  - Thermal properties of C/H-, C/H/O-, C/H/N- and C/H/X-grown polycrystalline CVD diamond. P. K. Bachmann, H. J. Hagemann, H. Lade,  ...
JF  - Diamond and Related Material. Vol 4. (1995), H. Issue 5-6
Y1  - 1995
SP  - 820
EP  - 826
PB  - Elsevier Science
CY  - New York, NY [u.a.]
ER  - 
TY  - JOUR
A1  - Hagemann, Hans-Jürgen
A1  - Bachmann, Peter K.
A1  - Lade, H.
A1  - Leers, D.
T1  - CVD Diamond Growth: Gas Compositions and Film Properties / P.K. Bachmann, H.J. Hagemann, H. Lade, D. Leers, D.U. Wiechert and H. Wilson
JF  - Advanced materials '94 : proceedings of the NIRIM International Symposium on Advanced Materials '94, Tsukuba, Japan, March 13 - 17, 1994 / National Institute for Research in Inorganic Materials. Ed. by M. Kamo ...
Y1  - 1994
N1  - NIRIM International Symposium on Advanced Materials ; 1994 (Tsukuba) : 1994.03.13-17
SP  - 115
EP  - 120
PB  - International Communications Specialists
CY  - Tokyo
ER  - 
TY  - CHAP
A1  - Poghossian, Arshak
A1  - Schusser, Sebastian
A1  - Bäcker, Matthias
A1  - Leinhos, Marcel
A1  - Schöning, Michael Josef
T1  - Real-time in-situ electrical monitoring of the degradation of biopolymers using semiconductor field-effect devices
T2  - Biodegradable biopolymers. Vol. 1
Y1  - 2015
SN  - 978-1-63483-632-6
SP  - 135
EP  - 153
PB  - Nova Science Publ.
CY  - Hauppauge
ER  - 
TY  - JOUR
A1  - Bergmann, Ole
A1  - Götten, Falk
A1  - Braun, Carsten
A1  - Janser, Frank
T1  - Comparison and evaluation of blade element methods against RANS simulations and test data
JF  - CEAS Aeronautical Journal
N2  - This paper compares several blade element theory (BET) method-based propeller simulation tools, including an evaluation against static propeller ground tests and high-fidelity Reynolds-Average Navier Stokes (RANS) simulations. Two proprietary propeller geometries for paraglider applications are analysed in static and flight conditions. The RANS simulations are validated with the static test data and used as a reference for comparing the BET in flight conditions. The comparison includes the analysis of varying 2D aerodynamic airfoil parameters and different induced velocity calculation methods. The evaluation of the BET propeller simulation tools shows the strength of the BET tools compared to RANS simulations. The RANS simulations underpredict static experimental data within 10% relative error, while appropriate BET tools overpredict the RANS results by 15–20% relative error. A variation in 2D aerodynamic data depicts the need for highly accurate 2D data for accurate BET results. The nonlinear BET coupled with XFOIL for the 2D aerodynamic data matches best with RANS in static operation and flight conditions. The novel BET tool PropCODE combines both approaches and offers further correction models for highly accurate static and flight condition results.
KW  - BET
KW  - CFD propeller simulation
KW  - Propeller aerodynamics
KW  - Actuator disk modelling
KW  - Propeller performance
Y1  - 2022
U6  - https://doi.org/10.1007/s13272-022-00579-1
SN  - 1869-5590 (Online)
SN  - 1869-5582 (Print)
N1  - Corresponding author: Ole Bergmann
VL  - 13
SP  - 535
EP  - 557
PB  - Springer
CY  - Wien
ER  - 
TY  - JOUR
A1  - Möhren, Felix
A1  - Bergmann, Ole
A1  - Janser, Frank
A1  - Braun, Carsten
T1  - On the influence of elasticity on propeller performance: a parametric study
JF  - CEAS Aeronautical Journal
N2  - The aerodynamic performance of propellers strongly depends on their geometry and, consequently, on aeroelastic deformations. Knowledge of the extent of the impact is crucial for overall aircraft performance. An integrated simulation environment for steady aeroelastic propeller simulations is presented. The simulation environment is applied to determine the impact of elastic deformations on the aerodynamic propeller performance. The aerodynamic module includes a blade element momentum approach to calculate aerodynamic loads. The structural module is based on finite beam elements, according to Timoshenko theory, including moderate deflections. Several fixed-pitch propellers with thin-walled cross sections made of both isotropic and non-isotropic materials are investigated. The essential parameters are varied: diameter, disc loading, sweep, material, rotational, and flight velocity. The relative change of thrust between rigid and elastic blades quantifies the impact of propeller elasticity. Swept propellers of large diameters or low disc loadings can decrease the thrust significantly. High flight velocities and low material stiffness amplify this tendency. Performance calculations without consideration of propeller elasticity can lead to decreased efficiency. To avoid cost- and time-intense redesigns, propeller elasticity should be considered for swept planforms and low disc loadings.
KW  - Propeller
KW  - Finite element method
KW  - Blade element method
KW  - Propeller elasticity
KW  - Aeroelasticity
Y1  - 2023
U6  - https://doi.org/10.1007/s13272-023-00649-y
SN  - 1869-5590 (Online)
SN  - 1869-5582 (Print)
N1  - Corresponding author: Felix Möhren
VL  - 14
SP  - 311
EP  - 323
PB  - Springer Nature
CY  - Berlin
ER  - 
TY  - JOUR
A1  - Stäudle, Benjamin
A1  - Seynnes, Olivier
A1  - Laps, Guido
A1  - Brüggemann, Gert-Peter
A1  - Albracht, Kirsten
T1  - Altered gastrocnemius contractile behavior in former achilles tendon rupture patients during walking
JF  - Frontiers in Physiology
N2  - Achilles tendon rupture (ATR) remains associated with functional limitations years after injury. Architectural remodeling of the gastrocnemius medialis (GM) muscle is typically observed in the affected leg and may compensate force deficits caused by a longer tendon. Yet patients seem to retain functional limitations during—low-force—walking gait. To explore the potential limits imposed by the remodeled GM muscle-tendon unit (MTU) on walking gait, we examined the contractile behavior of muscle fascicles during the stance phase. In a cross-sectional design, we studied nine former patients (males; age: 45 ± 9 years; height: 180 ± 7 cm; weight: 83 ± 6 kg) with a history of complete unilateral ATR, approximately 4 years post-surgery. Using ultrasonography, GM tendon morphology, muscle architecture at rest, and fascicular behavior were assessed during walking at 1.5 m⋅s–1 on a treadmill. Walking patterns were recorded with a motion capture system. The unaffected leg served as control. Lower limbs kinematics were largely similar between legs during walking. Typical features of ATR-related MTU remodeling were observed during the stance sub-phases corresponding to series elastic element (SEE) lengthening (energy storage) and SEE shortening (energy release), with shorter GM fascicles (36 and 36%, respectively) and greater pennation angles (8° and 12°, respectively). However, relative to the optimal fascicle length for force production, fascicles operated at comparable length in both legs. Similarly, when expressed relative to optimal fascicle length, fascicle contraction velocity was not different between sides, except at the time-point of peak series elastic element (SEE) length, where it was 39 ± 49% lower in the affected leg. Concomitantly, fascicles rotation during contraction was greater in the affected leg during the whole stance-phase, and architectural gear ratios (AGR) was larger during SEE lengthening. Under the present testing conditions, former ATR patients had recovered a relatively symmetrical walking gait pattern. Differences in seen AGR seem to accommodate the profound changes in MTU architecture, limiting the required fascicle shortening velocity. Overall, the contractile behavior of the GM fascicles does not restrict length- or velocity-dependent force potentials during this locomotor task.
KW  - tendon rupture
KW  - muscle fascicle behavior
KW  - walking gait
KW  - force generation
KW  - ultrasound imaging
Y1  - 2022
U6  - https://doi.org/10.3389/fphys.2022.792576
SN  - 1664-042X
VL  - 13
PB  - Frontiers Research Foundation
CY  - Lausanne
ER  - 
TY  - JOUR
A1  - Stäudle, Benjamin
A1  - Seynnes, Olivier
A1  - Laps, Guido
A1  - Göll, Fabian
A1  - Brüggemann, Gert-Peter
A1  - Albracht, Kirsten
T1  - Recovery from achilles tendon repair: a combination of Postsurgery Outcomes and Insufficient remodeling of muscle and tendon
JF  - Medicine & Science in Sports & Exercise
N2  - Achilles tendon rupture (ATR) patients have persistent functional deficits in the triceps surae muscle–tendon unit (MTU). The complex remodeling of the MTU accompanying these deficits remains poorly understood. The purpose of the present study was to associate in vivo and in silico data to investigate the relations between changes inMTU properties and strength deficits inATR patients. Methods: Elevenmale subjects who had undergone surgical repair of complete unilateral ATR were examined 4.6 ± 2.0 (mean ± SD) yr after rupture. Gastrocnemius medialis (GM) tendon stiffness, morphology, and muscle architecture were determined using ultrasonography. The force–length relation of the plantar flexor muscles was assessed at five ankle joint angles. In addition, simulations (OpenSim) of the GM MTU force–length properties were performed with various iterations of MTU properties found between the unaffected and the affected side. Results: The affected side of the patients displayed a longer, larger, and stiffer GM tendon (13% ± 10%, 105% ± 28%, and 54% ± 24%, respectively) compared with the unaffected side. The GM muscle fascicles of the affected side were shorter (32% ± 12%) and with greater pennation angles (31% ± 26%). A mean deficit in plantarflexion moment of 31% ± 10% was measured. Simulations indicate that pairing an intact muscle with a longer tendon shifts the optimal angular range of peak force outside physiological angular ranges, whereas the shorter muscle fascicles and tendon stiffening seen in the affected side decrease this shift, albeit incompletely. Conclusions: These results suggest that the substantial changes in MTU properties found in ATR patients may partly result from compensatory remodeling, although this process appears insufficient to fully restore muscle function.
KW  - Tendon Rupture
KW  - Stiffness
KW  - Simulation
KW  - Muscle Force
KW  - Muscle Fascicle
Y1  - 2021
U6  - https://doi.org/10.1249/MSS.0000000000002592
SN  - 1530-0315
VL  - 53
IS  - 7
SP  - 1356
EP  - 1366
PB  - American College of Sports Medicine
CY  - Philadelphia, Pa.
ER  - 
TY  - JOUR
A1  - Hagemann, Hans-Jürgen
A1  - Bachmann, Peter K.
A1  - Lade, H.
A1  - Leers, D.
T1  - Influence of the gas phase on diamond deposition and diamond properties. Bachmann, P. K.; Hagemann, H.J.; Lade, H.; Leers, D.; Picht, F.; Wiechert, D. U.
JF  - Advanced materials '94 : proceedings of the NIRIM International Symposium on Advanced Materials '94, Tsukuba, Japan, March 13 - 17, 1994 / National Institute for Research in Inorganic Materials. Ed. by M. Kamo
Y1  - 1994
N1  - NIRIM International Symposium on Advanced Materials ; <1994, Tsukuba>
SP  - 115
EP  - 120
PB  - International Communications Specialists, Inc.
CY  - Tokyo
ER  - 
TY  - CHAP
A1  - Stöbe, Rolf
A1  - Höfken, Hans-Wilhelm
A1  - Schuba, Marko
A1  - Breuer, Michael
T1  - Artificial ageing of mobile devices using a simulated GSM/GPRS network
T2  - Eighth International Conference on Availability, Reliability and Security (ARES) : 2-6 Sept. 2013, Regensburg
Y1  - 2013
SP  - 493
EP  - 497
PB  - IEEE
ER  -