---
_id: '29940'
abstract:
- lang: eng
text: A full-bridge modular multilevel converter (MMC) is compared to a half-bridge-based
MMC for high-current low-voltage DC-applications such as electrolysis, arc welding
or datacenters with DC-power distribution. Usually, modular multilevel converters
are used in high-voltage DC-applications (HVDC) in the multiple kV-range, but
to meet the needs of a high-current demand at low output voltage levels, the modular
converter concept requires adaptations. In the proposed concept, the MMC is used
to step-down the three-phase medium-voltage of 10 kV. Therefore, each module is
extended by an LLC resonant converter to adapt to the specific electrolyzers DC-voltage
range of 142-220V and to provide galvanic isolation. The proposed MMC converter
with full-bridge modules uses half the number of modules compared to a half-bridge-based
MMC while reducing the voltage ripple by 78% and capacitor losses by 64% by rearranging
the same components to ensure identical costs and volume. For additional reliability,
a new robust algorithm for balancing conduction losses during the bypass phase
is presented.
author:
- first_name: Roland
full_name: Unruh, Roland
id: '34289'
last_name: Unruh
- first_name: Frank
full_name: Schafmeister, Frank
id: '71291'
last_name: Schafmeister
- first_name: Norbert
full_name: Fröhleke, Norbert
last_name: Fröhleke
- first_name: Joachim
full_name: Böcker, Joachim
id: '66'
last_name: Böcker
orcid: 0000-0002-8480-7295
citation:
ama: 'Unruh R, Schafmeister F, Fröhleke N, Böcker J. 1-MW Full-Bridge MMC for High-Current
Low-Voltage (100V-400V) DC-Applications. In: PCIM Europe Digital Days 2020;
International Exhibition and Conference for Power Electronics, Intelligent Motion,
Renewable Energy and Energy Management. VDE; 2020.'
apa: Unruh, R., Schafmeister, F., Fröhleke, N., & Böcker, J. (2020). 1-MW Full-Bridge
MMC for High-Current Low-Voltage (100V-400V) DC-Applications. PCIM Europe Digital
Days 2020; International Exhibition and Conference for Power Electronics, Intelligent
Motion, Renewable Energy and Energy Management. PCIM Europe digital days 2020,
Germany.
bibtex: '@inproceedings{Unruh_Schafmeister_Fröhleke_Böcker_2020, title={1-MW Full-Bridge
MMC for High-Current Low-Voltage (100V-400V) DC-Applications}, booktitle={PCIM
Europe digital days 2020; International Exhibition and Conference for Power Electronics,
Intelligent Motion, Renewable Energy and Energy Management}, publisher={VDE},
author={Unruh, Roland and Schafmeister, Frank and Fröhleke, Norbert and Böcker,
Joachim}, year={2020} }'
chicago: Unruh, Roland, Frank Schafmeister, Norbert Fröhleke, and Joachim Böcker.
“1-MW Full-Bridge MMC for High-Current Low-Voltage (100V-400V) DC-Applications.”
In PCIM Europe Digital Days 2020; International Exhibition and Conference for
Power Electronics, Intelligent Motion, Renewable Energy and Energy Management.
VDE, 2020.
ieee: R. Unruh, F. Schafmeister, N. Fröhleke, and J. Böcker, “1-MW Full-Bridge MMC
for High-Current Low-Voltage (100V-400V) DC-Applications,” presented at the PCIM
Europe digital days 2020, Germany, 2020.
mla: Unruh, Roland, et al. “1-MW Full-Bridge MMC for High-Current Low-Voltage (100V-400V)
DC-Applications.” PCIM Europe Digital Days 2020; International Exhibition and
Conference for Power Electronics, Intelligent Motion, Renewable Energy and Energy
Management, VDE, 2020.
short: 'R. Unruh, F. Schafmeister, N. Fröhleke, J. Böcker, in: PCIM Europe Digital
Days 2020; International Exhibition and Conference for Power Electronics, Intelligent
Motion, Renewable Energy and Energy Management, VDE, 2020.'
conference:
end_date: 2020-07-08
location: Germany
name: PCIM Europe digital days 2020
start_date: 2020-07-07
date_created: 2022-02-21T16:42:30Z
date_updated: 2023-10-20T11:52:39Z
department:
- _id: '52'
keyword:
- Cascaded H-Bridge
- Solid-State Transformer
- Capacitor voltage ripple
- Zero sequence voltage
- Full-Bridge
language:
- iso: eng
main_file_link:
- url: https://ieeexplore.ieee.org/abstract/document/9178138
publication: PCIM Europe digital days 2020; International Exhibition and Conference
for Power Electronics, Intelligent Motion, Renewable Energy and Energy Management
publication_identifier:
isbn:
- 978-3-8007-5245-4
publication_status: published
publisher: VDE
status: public
title: 1-MW Full-Bridge MMC for High-Current Low-Voltage (100V-400V) DC-Applications
type: conference
user_id: '34289'
year: '2020'
...
---
_id: '64018'
abstract:
- lang: eng
text: CO oxidation is an extensively studied reaction in heterogeneous catalysis
due to its seeming simplicity and its great importance for emission control. However,
the role of particle size and more specifically structure sensitivity in this
reaction is still controversial. In the present study, colloidal “surfactant-free”
Pt nanoparticles (NPs) in a size regime of 1–4 nm with narrow size distribution
and control over particle size were synthesized and subsequently supported on
Al2O3 to prepare model catalysts. CO oxidation was performed using Pt NPs catalysts
with particles sizes of 1, 2, 3, and 4 nm at different reaction temperatures.
It is shown that the reaction exhibits a particle size effect that depends strongly
on the reaction conditions. At 170 °C, the reaction seems to proceed within the
same kinetic regime for all particle sizes, but the surface normalized activity
depends strongly on the particle size, with maximum activity for nanoparticles
2 nm in diameter. A temperature increase to 200 °C leads to a change of the kinetic
regime that depends on the particle size. For Pt NPs 1 nm in diameter a reaction
order of 1 for O2 was observed, indicating that O2 adsorbs molecularly and dissociates
in a following step, which represents the generally accepted mechanism on Pt surfaces.
The reaction order of −1 for CO demonstrates that the surface is saturated with
CO under reaction conditions. With increasing particle size, the reaction orders
of O2 and CO change. For particles 2 nm in size, an increase in temperature also
results in reaction orders of 1 for O2 and −1 for CO; NPs of 3 and 4 nm, even
at higher temperatures, show no clear kinetic behavior that can be explained by
a single reaction mechanism. Instead, the Boudouard reaction between two adjacent
adsorbed CO molecules was identified as an important additional reaction pathway
that occurs preferentially on large particles and causes more complex kinetics.
author:
- first_name: Sarah
full_name: Neumann, Sarah
last_name: Neumann
- first_name: Torsten
full_name: Gutmann, Torsten
id: '118165'
last_name: Gutmann
- first_name: Gerd
full_name: Buntkowsky, Gerd
last_name: Buntkowsky
- first_name: Stephen
full_name: Paul, Stephen
last_name: Paul
- first_name: Greg
full_name: Thiele, Greg
last_name: Thiele
- first_name: Heiko
full_name: Sievers, Heiko
last_name: Sievers
- first_name: Marcus
full_name: Bäumer, Marcus
last_name: Bäumer
- first_name: Sebastian
full_name: Kunz, Sebastian
last_name: Kunz
citation:
ama: Neumann S, Gutmann T, Buntkowsky G, et al. Insights into the reaction mechanism
and particle size effects of CO oxidation over supported Pt nanoparticle catalysts.
Journal of Catalysis. 2019;377:662–672. doi:10.1016/j.jcat.2019.07.049
apa: Neumann, S., Gutmann, T., Buntkowsky, G., Paul, S., Thiele, G., Sievers, H.,
Bäumer, M., & Kunz, S. (2019). Insights into the reaction mechanism and particle
size effects of CO oxidation over supported Pt nanoparticle catalysts. Journal
of Catalysis, 377, 662–672. https://doi.org/10.1016/j.jcat.2019.07.049
bibtex: '@article{Neumann_Gutmann_Buntkowsky_Paul_Thiele_Sievers_Bäumer_Kunz_2019,
title={Insights into the reaction mechanism and particle size effects of CO oxidation
over supported Pt nanoparticle catalysts}, volume={377}, DOI={10.1016/j.jcat.2019.07.049},
journal={Journal of Catalysis}, author={Neumann, Sarah and Gutmann, Torsten and
Buntkowsky, Gerd and Paul, Stephen and Thiele, Greg and Sievers, Heiko and Bäumer,
Marcus and Kunz, Sebastian}, year={2019}, pages={662–672} }'
chicago: 'Neumann, Sarah, Torsten Gutmann, Gerd Buntkowsky, Stephen Paul, Greg Thiele,
Heiko Sievers, Marcus Bäumer, and Sebastian Kunz. “Insights into the Reaction
Mechanism and Particle Size Effects of CO Oxidation over Supported Pt Nanoparticle
Catalysts.” Journal of Catalysis 377 (2019): 662–672. https://doi.org/10.1016/j.jcat.2019.07.049.'
ieee: 'S. Neumann et al., “Insights into the reaction mechanism and particle
size effects of CO oxidation over supported Pt nanoparticle catalysts,” Journal
of Catalysis, vol. 377, pp. 662–672, 2019, doi: 10.1016/j.jcat.2019.07.049.'
mla: Neumann, Sarah, et al. “Insights into the Reaction Mechanism and Particle Size
Effects of CO Oxidation over Supported Pt Nanoparticle Catalysts.” Journal
of Catalysis, vol. 377, 2019, pp. 662–672, doi:10.1016/j.jcat.2019.07.049.
short: S. Neumann, T. Gutmann, G. Buntkowsky, S. Paul, G. Thiele, H. Sievers, M.
Bäumer, S. Kunz, Journal of Catalysis 377 (2019) 662–672.
date_created: 2026-02-07T16:02:06Z
date_updated: 2026-02-17T16:14:45Z
doi: 10.1016/j.jcat.2019.07.049
extern: '1'
intvolume: ' 377'
keyword:
- Solid state NMR
- “Surfactant-free” platinum nanoparticles
- CO oxidation
- Particle size effect
- Structure sensitivity
language:
- iso: eng
page: 662–672
publication: Journal of Catalysis
status: public
title: Insights into the reaction mechanism and particle size effects of CO oxidation
over supported Pt nanoparticle catalysts
type: journal_article
user_id: '100715'
volume: 377
year: '2019'
...
---
_id: '63960'
abstract:
- lang: eng
text: Recent advances in solid-state nuclear magnetic resonance (NMR) spectroscopy
and dynamic nuclear polarization (DNP) of nanostructured materials are reviewed.
A first group of materials is based on crystalline nanocellulose (CNC) or microcrystalline
cellulose (MCC), which are used as carrier materials for dye molecules, catalysts
or in combination with heterocyclic molecules as ion conducting membranes. These
materials have widespread applications in sensorics, optics, catalysis or fuel
cell research. A second group are metal oxides such as V-Mo-W oxides, which are
of enormous importance in the manufacturing process of basic chemicals. The third
group are catalytically active nanocrystalline metal nanoparticles, coated with
protectants or embedded in polymers. The last group includes of lead-free perovskite
materials, which are employed as environmentally benign substitution materials
for conventional lead-based electronics materials. These materials are discussed
in terms of their application and physico-chemical characterization by solid-state
NMR techniques, combined with gas-phase NMR and quantum-chemical modelling on
the density functional theory (DFT) level. The application of multinuclear 1H,
2H, 13C, 15N and 23Na solid state NMR techniques under static or MAS conditions
for the characterization of these materials, their surfaces and processes on their
surfaces is discussed. Moreover, the analytic power of the combination of these
techniques with DNP for the identification of low-concentrated carbon and nitrogen
containing surface species in natural abundance is reviewed. Finally, approaches
for sensitivity enhancement by DNP of quadrupolar nuclei such as 17O and 51V are
presented that enable the identification of catalytic sites in metal oxide catalysts.
author:
- first_name: Torsten
full_name: Gutmann, Torsten
id: '118165'
last_name: Gutmann
- first_name: Pedro B.
full_name: Groszewicz, Pedro B.
last_name: Groszewicz
- first_name: Gerd
full_name: Buntkowsky, Gerd
last_name: Buntkowsky
citation:
ama: Gutmann T, Groszewicz PB, Buntkowsky G. Solid-state NMR of nanocrystals. Annual
Reports on NMR Spectroscopy. 2019;97:1–82. doi:10.1016/bs.arnmr.2018.12.001
apa: Gutmann, T., Groszewicz, P. B., & Buntkowsky, G. (2019). Solid-state NMR
of nanocrystals. Annual Reports on NMR Spectroscopy, 97, 1–82. https://doi.org/10.1016/bs.arnmr.2018.12.001
bibtex: '@article{Gutmann_Groszewicz_Buntkowsky_2019, title={Solid-state NMR of
nanocrystals}, volume={97}, DOI={10.1016/bs.arnmr.2018.12.001},
journal={Annual Reports on NMR Spectroscopy}, author={Gutmann, Torsten and Groszewicz,
Pedro B. and Buntkowsky, Gerd}, year={2019}, pages={1–82} }'
chicago: 'Gutmann, Torsten, Pedro B. Groszewicz, and Gerd Buntkowsky. “Solid-State
NMR of Nanocrystals.” Annual Reports on NMR Spectroscopy 97 (2019): 1–82.
https://doi.org/10.1016/bs.arnmr.2018.12.001.'
ieee: 'T. Gutmann, P. B. Groszewicz, and G. Buntkowsky, “Solid-state NMR of nanocrystals,”
Annual Reports on NMR Spectroscopy, vol. 97, pp. 1–82, 2019, doi: 10.1016/bs.arnmr.2018.12.001.'
mla: Gutmann, Torsten, et al. “Solid-State NMR of Nanocrystals.” Annual Reports
on NMR Spectroscopy, vol. 97, 2019, pp. 1–82, doi:10.1016/bs.arnmr.2018.12.001.
short: T. Gutmann, P.B. Groszewicz, G. Buntkowsky, Annual Reports on NMR Spectroscopy
97 (2019) 1–82.
date_created: 2026-02-07T15:37:03Z
date_updated: 2026-02-17T16:17:56Z
doi: 10.1016/bs.arnmr.2018.12.001
extern: '1'
intvolume: ' 97'
keyword:
- solid-state nmr
- heterogeneous catalysis
- dynamic nuclear polarization
- Ferroelectrics
- Nanocatalysis
- Surface reactions
language:
- iso: eng
page: 1–82
publication: Annual Reports on NMR Spectroscopy
status: public
title: Solid-state NMR of nanocrystals
type: journal_article
user_id: '100715'
volume: 97
year: '2019'
...
---
_id: '8167'
author:
- first_name: Sevag
full_name: Gharibian, Sevag
id: '71541'
last_name: Gharibian
orcid: 0000-0002-9992-3379
- first_name: Jamie
full_name: Sikora, Jamie
last_name: Sikora
citation:
ama: Gharibian S, Sikora J. Ground State Connectivity of Local Hamiltonians. ACM
Transactions on Computation Theory (TOCT). 2018;10(2):8:1-8:28. doi:10.1145/3186587
apa: Gharibian, S., & Sikora, J. (2018). Ground State Connectivity of Local
Hamiltonians. ACM Transactions on Computation Theory (TOCT), 10(2),
8:1-8:28. https://doi.org/10.1145/3186587
bibtex: '@article{Gharibian_Sikora_2018, title={Ground State Connectivity of Local
Hamiltonians}, volume={10}, DOI={10.1145/3186587},
number={2}, journal={ACM Transactions on Computation Theory (TOCT)}, publisher={ACM},
author={Gharibian, Sevag and Sikora, Jamie}, year={2018}, pages={8:1-8:28} }'
chicago: 'Gharibian, Sevag, and Jamie Sikora. “Ground State Connectivity of Local
Hamiltonians.” ACM Transactions on Computation Theory (TOCT) 10, no. 2
(2018): 8:1-8:28. https://doi.org/10.1145/3186587.'
ieee: 'S. Gharibian and J. Sikora, “Ground State Connectivity of Local Hamiltonians,”
ACM Transactions on Computation Theory (TOCT), vol. 10, no. 2, p. 8:1-8:28,
2018, doi: 10.1145/3186587.'
mla: Gharibian, Sevag, and Jamie Sikora. “Ground State Connectivity of Local Hamiltonians.”
ACM Transactions on Computation Theory (TOCT), vol. 10, no. 2, ACM, 2018,
p. 8:1-8:28, doi:10.1145/3186587.
short: S. Gharibian, J. Sikora, ACM Transactions on Computation Theory (TOCT) 10
(2018) 8:1-8:28.
date_created: 2019-03-01T11:49:31Z
date_updated: 2023-02-28T11:01:36Z
department:
- _id: '623'
- _id: '7'
doi: 10.1145/3186587
external_id:
arxiv:
- '1409.3182'
intvolume: ' 10'
issue: '2'
keyword:
- Local Hamiltonian
- ground state connectivity
- quantum Hamiltonian complexity
- reconfiguration problem
language:
- iso: eng
main_file_link:
- open_access: '1'
url: https://arxiv.org/abs/1409.3182
oa: '1'
page: 8:1-8:28
publication: ACM Transactions on Computation Theory (TOCT)
publication_identifier:
issn:
- 1942-3454
publication_status: published
publisher: ACM
status: public
title: Ground State Connectivity of Local Hamiltonians
type: journal_article
user_id: '71541'
volume: 10
year: '2018'
...
---
_id: '64053'
abstract:
- lang: eng
text: The utilization and preparation of functional hybrid films for optical sensing
applications and membranes is of utmost importance. In this work, we report the
convenient and scalable preparation of self-crosslinking particle-based films
derived by directed self-assembly of alkoxysilane-based cross-linkers as part
of a core-shell particle architecture. The synthesis of well-designed monodisperse
core-shell particles by emulsion polymerization is the basic prerequisite for
subsequent particle processing via the melt-shear organization technique. In more
detail, the core particles consist of polystyrene (PS) or poly(methyl methacrylate)
(PMMA), while the comparably soft particle shell consists of poly(ethyl acrylate)
(PEA) and different alkoxysilane-based poly(methacrylate)s. For hybrid film formation
and convenient self-cross-linking, different alkyl groups at the siloxane moieties
were investigated in detail by solid-state Magic-Angle Spinning Nuclear Magnetic
Resonance (MAS, NMR) spectroscopy revealing different crosslinking capabilities,
which strongly influence the properties of the core or shell particle films with
respect to transparency and iridescent reflection colors. Furthermore, solid-state
NMR spectroscopy and investigation of the thermal properties by differential scanning
calorimetry (DSC) measurements allow for insights into the cross-linking capabilities
prior to and after synthesis, as well as after the thermally and pressure-induced
processing steps. Subsequently, free-standing and self-crosslinked particle-based
films featuring excellent particle order are obtained by application of the melt-shear
organization technique, as shown by microscopy (TEM, SEM).
author:
- first_name: S.
full_name: Vowinkel, S.
last_name: Vowinkel
- first_name: S.
full_name: Paul, S.
last_name: Paul
- first_name: Torsten
full_name: Gutmann, Torsten
id: '118165'
last_name: Gutmann
- first_name: M.
full_name: Gallei, M.
last_name: Gallei
citation:
ama: Vowinkel S, Paul S, Gutmann T, Gallei M. Free-Standing and Self-Crosslinkable
Hybrid Films by Core-Shell Particle Design and Processing. Nanomaterials.
2017;7(11):390. doi:10.3390/nano7110390
apa: Vowinkel, S., Paul, S., Gutmann, T., & Gallei, M. (2017). Free-Standing
and Self-Crosslinkable Hybrid Films by Core-Shell Particle Design and Processing.
Nanomaterials, 7(11), 390. https://doi.org/10.3390/nano7110390
bibtex: '@article{Vowinkel_Paul_Gutmann_Gallei_2017, title={Free-Standing and Self-Crosslinkable
Hybrid Films by Core-Shell Particle Design and Processing}, volume={7}, DOI={10.3390/nano7110390}, number={11},
journal={Nanomaterials}, author={Vowinkel, S. and Paul, S. and Gutmann, Torsten
and Gallei, M.}, year={2017}, pages={390} }'
chicago: 'Vowinkel, S., S. Paul, Torsten Gutmann, and M. Gallei. “Free-Standing
and Self-Crosslinkable Hybrid Films by Core-Shell Particle Design and Processing.”
Nanomaterials 7, no. 11 (2017): 390. https://doi.org/10.3390/nano7110390.'
ieee: 'S. Vowinkel, S. Paul, T. Gutmann, and M. Gallei, “Free-Standing and Self-Crosslinkable
Hybrid Films by Core-Shell Particle Design and Processing,” Nanomaterials,
vol. 7, no. 11, p. 390, 2017, doi: 10.3390/nano7110390.'
mla: Vowinkel, S., et al. “Free-Standing and Self-Crosslinkable Hybrid Films by
Core-Shell Particle Design and Processing.” Nanomaterials, vol. 7, no.
11, 2017, p. 390, doi:10.3390/nano7110390.
short: S. Vowinkel, S. Paul, T. Gutmann, M. Gallei, Nanomaterials 7 (2017) 390.
date_created: 2026-02-07T16:15:23Z
date_updated: 2026-02-17T16:12:54Z
doi: 10.3390/nano7110390
extern: '1'
intvolume: ' 7'
issue: '11'
keyword:
- Materials Science
- Science & Technology - Other Topics
- solid-state nmr
- spectroscopy
- catalysts
- colloidal crystals
- colloids
- cross-linking
- elastomeric opal films
- emulsion polymerization
- gamma-methacryloxypropyltrimethoxysilane
- hybrid films
- melt-shear organization
- nanoparticles
- particle
- photons
- polymers
- processing
- self-assembly
- transition
language:
- iso: eng
page: '390'
publication: Nanomaterials
publication_identifier:
issn:
- 2079-4991
status: public
title: Free-Standing and Self-Crosslinkable Hybrid Films by Core-Shell Particle Design
and Processing
type: journal_article
user_id: '100715'
volume: 7
year: '2017'
...
---
_id: '63956'
abstract:
- lang: eng
text: The synthesis of novel robust and stable iridium-based immobilized catalysts
on silica-polymer hybrid materials (Si-PB-Ir) is described. These catalysts are
characterized by a combination of 1D P-31 CP-MAS and 2D P-31-H-1 HETCOR and J-resolved
multinuclear solid state NMR experiments. Different binding situations such as
singly and multiply coordinated phosphines are identified. Density functional
theory (DFT) calculations are performed to corroborate the interpretation of the
experimental NMR data, in order to propose a structural model of the heterogenized
catalysts. Finally, the catalytic activity of the Si-PB-Ir catalysts is investigated
for the hydrogenation of styrene employing para-enriched hydrogen gas.
author:
- first_name: Torsten
full_name: Gutmann, Torsten
id: '118165'
last_name: Gutmann
- first_name: S.
full_name: Alkhagani, S.
last_name: Alkhagani
- first_name: N.
full_name: Rothermel, N.
last_name: Rothermel
- first_name: H. H.
full_name: Limbach, H. H.
last_name: Limbach
- first_name: H.
full_name: Breitzke, H.
last_name: Breitzke
- first_name: G.
full_name: Buntkowsky, G.
last_name: Buntkowsky
citation:
ama: Gutmann T, Alkhagani S, Rothermel N, Limbach HH, Breitzke H, Buntkowsky G.
P-31-Solid-State NMR Characterization and Catalytic Hydrogenation Tests of Novel
heterogenized Iridium-Catalysts. Zeitschrift Fur Physikalische Chemie-International
Journal of Research in Physical Chemistry & Chemical Physics. 2017;231(3):653–669.
doi:10.1515/zpch-2016-0837
apa: Gutmann, T., Alkhagani, S., Rothermel, N., Limbach, H. H., Breitzke, H., &
Buntkowsky, G. (2017). P-31-Solid-State NMR Characterization and Catalytic Hydrogenation
Tests of Novel heterogenized Iridium-Catalysts. Zeitschrift Fur Physikalische
Chemie-International Journal of Research in Physical Chemistry & Chemical
Physics, 231(3), 653–669. https://doi.org/10.1515/zpch-2016-0837
bibtex: '@article{Gutmann_Alkhagani_Rothermel_Limbach_Breitzke_Buntkowsky_2017,
title={P-31-Solid-State NMR Characterization and Catalytic Hydrogenation Tests
of Novel heterogenized Iridium-Catalysts}, volume={231}, DOI={10.1515/zpch-2016-0837},
number={3}, journal={Zeitschrift Fur Physikalische Chemie-International Journal
of Research in Physical Chemistry & Chemical Physics}, author={Gutmann, Torsten
and Alkhagani, S. and Rothermel, N. and Limbach, H. H. and Breitzke, H. and Buntkowsky,
G.}, year={2017}, pages={653–669} }'
chicago: 'Gutmann, Torsten, S. Alkhagani, N. Rothermel, H. H. Limbach, H. Breitzke,
and G. Buntkowsky. “P-31-Solid-State NMR Characterization and Catalytic Hydrogenation
Tests of Novel Heterogenized Iridium-Catalysts.” Zeitschrift Fur Physikalische
Chemie-International Journal of Research in Physical Chemistry & Chemical
Physics 231, no. 3 (2017): 653–669. https://doi.org/10.1515/zpch-2016-0837.'
ieee: 'T. Gutmann, S. Alkhagani, N. Rothermel, H. H. Limbach, H. Breitzke, and G.
Buntkowsky, “P-31-Solid-State NMR Characterization and Catalytic Hydrogenation
Tests of Novel heterogenized Iridium-Catalysts,” Zeitschrift Fur Physikalische
Chemie-International Journal of Research in Physical Chemistry & Chemical
Physics, vol. 231, no. 3, pp. 653–669, 2017, doi: 10.1515/zpch-2016-0837.'
mla: Gutmann, Torsten, et al. “P-31-Solid-State NMR Characterization and Catalytic
Hydrogenation Tests of Novel Heterogenized Iridium-Catalysts.” Zeitschrift
Fur Physikalische Chemie-International Journal of Research in Physical Chemistry
& Chemical Physics, vol. 231, no. 3, 2017, pp. 653–669, doi:10.1515/zpch-2016-0837.
short: T. Gutmann, S. Alkhagani, N. Rothermel, H.H. Limbach, H. Breitzke, G. Buntkowsky,
Zeitschrift Fur Physikalische Chemie-International Journal of Research in Physical
Chemistry & Chemical Physics 231 (2017) 653–669.
date_created: 2026-02-07T15:35:41Z
date_updated: 2026-02-17T16:18:04Z
doi: 10.1515/zpch-2016-0837
extern: '1'
intvolume: ' 231'
issue: '3'
keyword:
- Chemistry
- dynamic nuclear-polarization
- solid-state nmr
- DFT
- heterogeneous catalysis
- hydrido complexes
- hydrogenation
- immobilized catalyst
- inorganic hybrid
- iridium
- materials
- mesoporous
- molecular-orbital methods
- PHIP
- phosphine complexes
- reusable catalysts
- silica
- solid-state-NMR
- wilkinsons catalyst
language:
- iso: eng
page: 653–669
publication: Zeitschrift Fur Physikalische Chemie-International Journal of Research
in Physical Chemistry & Chemical Physics
publication_identifier:
issn:
- 0942-9352
status: public
title: P-31-Solid-State NMR Characterization and Catalytic Hydrogenation Tests of
Novel heterogenized Iridium-Catalysts
type: journal_article
user_id: '100715'
volume: 231
year: '2017'
...
---
_id: '63920'
abstract:
- lang: eng
text: Coordinatively unsaturated sites (CUS) present a key feature of alumina based
catalysts as they are believed to act as Lewis-acid sites in heterogeneously catalyzed
reactions. In the present study, the direct observation of active species on a
fluoride-doped aluminum oxide catalyst is demonstrated. This new fluoride-doped
aluminum oxide exhibits strong Lewis-acid sites and superior catalytic activity
as compared to gamma-Al2O3. To emphasize the labile state of Lewis-acid sites,
two distinctive states of the catalysts surface are addressed using H-1-Al-27
cross polarization (CP) MAS NMR. On the one hand, the highly dehydrated and active
state after calcination at 700 degrees C and on the other hand the rehydrated
and catalytically inactive surface (produced by contact to air) are probed. These
experiments revealed the presence of significant amounts of coordinatively unsaturated
sites in the form of 4-and 5-fold coordinated Al-sites on the highly dehydrated
surface. In contrast to this, the rehydrated sample exhibited a severely restructured
surface caused by the chemisorption of H2O which is ’constituted in a manner that
was proposed in earlier models for gamma-Al2O3 surfaces.
author:
- first_name: L.
full_name: Ahrem, L.
last_name: Ahrem
- first_name: G.
full_name: Scholz, G.
last_name: Scholz
- first_name: Torsten
full_name: Gutmann, Torsten
id: '118165'
last_name: Gutmann
- first_name: B.
full_name: Calvo, B.
last_name: Calvo
- first_name: G.
full_name: Buntkowsky, G.
last_name: Buntkowsky
- first_name: E.
full_name: Kemnitz, E.
last_name: Kemnitz
citation:
ama: Ahrem L, Scholz G, Gutmann T, Calvo B, Buntkowsky G, Kemnitz E. Direct Observation
of Coordinatively Unsaturated Sites on the Surface of a Fluoride-Doped Alumina
Catalyst. Journal of Physical Chemistry C. 2017;121(22):12206–12213. doi:10.1021/acs.jpcc.7b02535
apa: Ahrem, L., Scholz, G., Gutmann, T., Calvo, B., Buntkowsky, G., & Kemnitz,
E. (2017). Direct Observation of Coordinatively Unsaturated Sites on the Surface
of a Fluoride-Doped Alumina Catalyst. Journal of Physical Chemistry C,
121(22), 12206–12213. https://doi.org/10.1021/acs.jpcc.7b02535
bibtex: '@article{Ahrem_Scholz_Gutmann_Calvo_Buntkowsky_Kemnitz_2017, title={Direct
Observation of Coordinatively Unsaturated Sites on the Surface of a Fluoride-Doped
Alumina Catalyst}, volume={121}, DOI={10.1021/acs.jpcc.7b02535},
number={22}, journal={Journal of Physical Chemistry C}, author={Ahrem, L. and
Scholz, G. and Gutmann, Torsten and Calvo, B. and Buntkowsky, G. and Kemnitz,
E.}, year={2017}, pages={12206–12213} }'
chicago: 'Ahrem, L., G. Scholz, Torsten Gutmann, B. Calvo, G. Buntkowsky, and E.
Kemnitz. “Direct Observation of Coordinatively Unsaturated Sites on the Surface
of a Fluoride-Doped Alumina Catalyst.” Journal of Physical Chemistry C
121, no. 22 (2017): 12206–12213. https://doi.org/10.1021/acs.jpcc.7b02535.'
ieee: 'L. Ahrem, G. Scholz, T. Gutmann, B. Calvo, G. Buntkowsky, and E. Kemnitz,
“Direct Observation of Coordinatively Unsaturated Sites on the Surface of a Fluoride-Doped
Alumina Catalyst,” Journal of Physical Chemistry C, vol. 121, no. 22, pp.
12206–12213, 2017, doi: 10.1021/acs.jpcc.7b02535.'
mla: Ahrem, L., et al. “Direct Observation of Coordinatively Unsaturated Sites on
the Surface of a Fluoride-Doped Alumina Catalyst.” Journal of Physical Chemistry
C, vol. 121, no. 22, 2017, pp. 12206–12213, doi:10.1021/acs.jpcc.7b02535.
short: L. Ahrem, G. Scholz, T. Gutmann, B. Calvo, G. Buntkowsky, E. Kemnitz, Journal
of Physical Chemistry C 121 (2017) 12206–12213.
date_created: 2026-02-07T08:56:18Z
date_updated: 2026-02-17T16:19:24Z
doi: 10.1021/acs.jpcc.7b02535
extern: '1'
intvolume: ' 121'
issue: '22'
keyword:
- al-27 nmr
- characterization
- Chemistry
- cross-polarization
- dynamic nuclear-polarization
- eta-alumina
- gamma-alumina
- hydroxy fluorides
- ions
- Materials Science
- pentacoordinated al3+
- Science & Technology - Other Topics
- solid-state nmr
- spectroscopic
- structural insights
language:
- iso: eng
page: 12206–12213
publication: Journal of Physical Chemistry C
publication_identifier:
issn:
- 1932-7447
status: public
title: Direct Observation of Coordinatively Unsaturated Sites on the Surface of a
Fluoride-Doped Alumina Catalyst
type: journal_article
user_id: '100715'
volume: 121
year: '2017'
...
---
_id: '11917'
abstract:
- lang: eng
text: In this paper we present a speech presence probability (SPP) estimation algorithmwhich
exploits both temporal and spectral correlations of speech. To this end, the SPP
estimation is formulated as the posterior probability estimation of the states
of a two-dimensional (2D) Hidden Markov Model (HMM). We derive an iterative algorithm
to decode the 2D-HMM which is based on the turbo principle. The experimental results
show that indeed the SPP estimates improve from iteration to iteration, and further
clearly outperform another state-of-the-art SPP estimation algorithm.
author:
- first_name: Dang Hai Tran
full_name: Vu, Dang Hai Tran
last_name: Vu
- first_name: Reinhold
full_name: Haeb-Umbach, Reinhold
id: '242'
last_name: Haeb-Umbach
citation:
ama: 'Vu DHT, Haeb-Umbach R. Using the turbo principle for exploiting temporal and
spectral correlations in speech presence probability estimation. In: 38th International
Conference on Acoustics, Speech and Signal Processing (ICASSP 2013). ; 2013:863-867.
doi:10.1109/ICASSP.2013.6637771'
apa: Vu, D. H. T., & Haeb-Umbach, R. (2013). Using the turbo principle for exploiting
temporal and spectral correlations in speech presence probability estimation.
In 38th International Conference on Acoustics, Speech and Signal Processing
(ICASSP 2013) (pp. 863–867). https://doi.org/10.1109/ICASSP.2013.6637771
bibtex: '@inproceedings{Vu_Haeb-Umbach_2013, title={Using the turbo principle for
exploiting temporal and spectral correlations in speech presence probability estimation},
DOI={10.1109/ICASSP.2013.6637771},
booktitle={38th International Conference on Acoustics, Speech and Signal Processing
(ICASSP 2013)}, author={Vu, Dang Hai Tran and Haeb-Umbach, Reinhold}, year={2013},
pages={863–867} }'
chicago: Vu, Dang Hai Tran, and Reinhold Haeb-Umbach. “Using the Turbo Principle
for Exploiting Temporal and Spectral Correlations in Speech Presence Probability
Estimation.” In 38th International Conference on Acoustics, Speech and Signal
Processing (ICASSP 2013), 863–67, 2013. https://doi.org/10.1109/ICASSP.2013.6637771.
ieee: D. H. T. Vu and R. Haeb-Umbach, “Using the turbo principle for exploiting
temporal and spectral correlations in speech presence probability estimation,”
in 38th International Conference on Acoustics, Speech and Signal Processing
(ICASSP 2013), 2013, pp. 863–867.
mla: Vu, Dang Hai Tran, and Reinhold Haeb-Umbach. “Using the Turbo Principle for
Exploiting Temporal and Spectral Correlations in Speech Presence Probability Estimation.”
38th International Conference on Acoustics, Speech and Signal Processing (ICASSP
2013), 2013, pp. 863–67, doi:10.1109/ICASSP.2013.6637771.
short: 'D.H.T. Vu, R. Haeb-Umbach, in: 38th International Conference on Acoustics,
Speech and Signal Processing (ICASSP 2013), 2013, pp. 863–867.'
date_created: 2019-07-12T05:30:45Z
date_updated: 2022-01-06T06:51:12Z
department:
- _id: '54'
doi: 10.1109/ICASSP.2013.6637771
keyword:
- correlation methods
- estimation theory
- hidden Markov models
- iterative methods
- probability
- spectral analysis
- speech processing
- 2D HMM
- SPP estimates
- iterative algorithm
- posterior probability estimation
- spectral correlation
- speech presence probability estimation
- state-of-the-art SPP estimation algorithm
- temporal correlation
- turbo principle
- two-dimensional hidden Markov model
- Correlation
- Decoding
- Estimation
- Iterative decoding
- Noise
- Speech
- Vectors
language:
- iso: eng
page: 863-867
publication: 38th International Conference on Acoustics, Speech and Signal Processing
(ICASSP 2013)
publication_identifier:
issn:
- 1520-6149
status: public
title: Using the turbo principle for exploiting temporal and spectral correlations
in speech presence probability estimation
type: conference
user_id: '44006'
year: '2013'
...
---
_id: '9784'
abstract:
- lang: eng
text: Piezoelectric inertia motors use the inertia of a body to drive it by means
of a friction contact in a series of small steps. These motors can operate in
``stick-slip'' or ``slip-slip'' mode, with the fundamental frequency of the driving
signal ranging from several Hertz to more than 100 kHz. To predict the motor characteristics,
a Coulomb friction model is sufficient in many cases, but numerical simulation
requires microscopic time steps. This contribution proposes a much faster simulation
technique using one evaluation per period of the excitation signal. The proposed
technique produces results very close to those of timestep simulation for ultrasonics
inertia motors and allows direct determination of the steady-state velocity of
an inertia motor from the motion profile of the driving part. Thus it is a useful
simulation technique which can be applied in both analysis and design of inertia
motors, especially for parameter studies and optimisation.
author:
- first_name: Matthias
full_name: Hunstig, Matthias
last_name: Hunstig
- first_name: Tobias
full_name: Hemsel, Tobias
last_name: Hemsel
- first_name: Walter
full_name: Sextro, Walter
last_name: Sextro
citation:
ama: 'Hunstig M, Hemsel T, Sextro W. An efficient simulation technique for high-frequency
piezoelectric inertia motors. In: Ultrasonics Symposium (IUS), 2012 IEEE International.
; 2012:277-280. doi:10.1109/ULTSYM.2012.0068'
apa: Hunstig, M., Hemsel, T., & Sextro, W. (2012). An efficient simulation technique
for high-frequency piezoelectric inertia motors. In Ultrasonics Symposium (IUS),
2012 IEEE International (pp. 277–280). https://doi.org/10.1109/ULTSYM.2012.0068
bibtex: '@inproceedings{Hunstig_Hemsel_Sextro_2012, title={An efficient simulation
technique for high-frequency piezoelectric inertia motors}, DOI={10.1109/ULTSYM.2012.0068},
booktitle={Ultrasonics Symposium (IUS), 2012 IEEE International}, author={Hunstig,
Matthias and Hemsel, Tobias and Sextro, Walter}, year={2012}, pages={277–280}
}'
chicago: Hunstig, Matthias, Tobias Hemsel, and Walter Sextro. “An Efficient Simulation
Technique for High-Frequency Piezoelectric Inertia Motors.” In Ultrasonics
Symposium (IUS), 2012 IEEE International, 277–80, 2012. https://doi.org/10.1109/ULTSYM.2012.0068.
ieee: M. Hunstig, T. Hemsel, and W. Sextro, “An efficient simulation technique for
high-frequency piezoelectric inertia motors,” in Ultrasonics Symposium (IUS),
2012 IEEE International, 2012, pp. 277–280.
mla: Hunstig, Matthias, et al. “An Efficient Simulation Technique for High-Frequency
Piezoelectric Inertia Motors.” Ultrasonics Symposium (IUS), 2012 IEEE International,
2012, pp. 277–80, doi:10.1109/ULTSYM.2012.0068.
short: 'M. Hunstig, T. Hemsel, W. Sextro, in: Ultrasonics Symposium (IUS), 2012
IEEE International, 2012, pp. 277–280.'
date_created: 2019-05-13T13:20:17Z
date_updated: 2022-01-06T07:04:20Z
department:
- _id: '151'
doi: 10.1109/ULTSYM.2012.0068
keyword:
- friction
- ultrasonic motors
- Coulomb friction model
- efficient simulation technique
- friction contact
- high-frequency piezoelectric inertia motor
- motor characteristics prediction
- numerical simulation
- slip-slip mode
- stick-slip mode
- time-step simulation
- ultrasonic inertia motor
- Acceleration
- Acoustics
- Actuators
- Computational modeling
- Friction
- Numerical models
- Steady-state
language:
- iso: eng
page: 277-280
publication: Ultrasonics Symposium (IUS), 2012 IEEE International
publication_identifier:
issn:
- 1948-5719
quality_controlled: '1'
status: public
title: An efficient simulation technique for high-frequency piezoelectric inertia
motors
type: conference
user_id: '55222'
year: '2012'
...
---
_id: '11726'
abstract:
- lang: eng
text: In this paper we present a robust location estimation algorithm especially
focused on the accuracy in vertical position. A loosely-coupled error state space
Kalman filter, which fuses sensor data of an Inertial Measurement Unit and the
output of a Global Positioning System device, is augmented by height information
from an altitude measurement unit. This unit consists of a barometric altimeter
whose output is fused with topographic map information by a Kalman filter to provide
robust information about the current vertical user position. These data replace
the less reliable vertical position information provided the GPS device. It is
shown that typical barometric errors like thermal divergences and fluctuations
in the pressure due to changing weather conditions can be compensated by the topographic
map information and the barometric error Kalman filter. The resulting height information
is shown not only to be more reliable than height information provided by GPS.
It also turns out that it leads to better attitude and thus better overall localization
estimation accuracy due to the coupling of spatial orientations via the Direct
Cosine Matrix. Results are presented both for artificially generated and field
test data, where the user is moving by car.
author:
- first_name: Maik
full_name: Bevermeier, Maik
last_name: Bevermeier
- first_name: Oliver
full_name: Walter, Oliver
last_name: Walter
- first_name: Sven
full_name: Peschke, Sven
last_name: Peschke
- first_name: Reinhold
full_name: Haeb-Umbach, Reinhold
id: '242'
last_name: Haeb-Umbach
citation:
ama: 'Bevermeier M, Walter O, Peschke S, Haeb-Umbach R. Barometric height estimation
combined with map-matching in a loosely-coupled Kalman-filter. In: 7th Workshop
on Positioning Navigation and Communication (WPNC 2010). ; 2010:128-134. doi:10.1109/WPNC.2010.5650745'
apa: Bevermeier, M., Walter, O., Peschke, S., & Haeb-Umbach, R. (2010). Barometric
height estimation combined with map-matching in a loosely-coupled Kalman-filter.
In 7th Workshop on Positioning Navigation and Communication (WPNC 2010)
(pp. 128–134). https://doi.org/10.1109/WPNC.2010.5650745
bibtex: '@inproceedings{Bevermeier_Walter_Peschke_Haeb-Umbach_2010, title={Barometric
height estimation combined with map-matching in a loosely-coupled Kalman-filter},
DOI={10.1109/WPNC.2010.5650745},
booktitle={7th Workshop on Positioning Navigation and Communication (WPNC 2010)},
author={Bevermeier, Maik and Walter, Oliver and Peschke, Sven and Haeb-Umbach,
Reinhold}, year={2010}, pages={128–134} }'
chicago: Bevermeier, Maik, Oliver Walter, Sven Peschke, and Reinhold Haeb-Umbach.
“Barometric Height Estimation Combined with Map-Matching in a Loosely-Coupled
Kalman-Filter.” In 7th Workshop on Positioning Navigation and Communication
(WPNC 2010), 128–34, 2010. https://doi.org/10.1109/WPNC.2010.5650745.
ieee: M. Bevermeier, O. Walter, S. Peschke, and R. Haeb-Umbach, “Barometric height
estimation combined with map-matching in a loosely-coupled Kalman-filter,” in
7th Workshop on Positioning Navigation and Communication (WPNC 2010), 2010,
pp. 128–134.
mla: Bevermeier, Maik, et al. “Barometric Height Estimation Combined with Map-Matching
in a Loosely-Coupled Kalman-Filter.” 7th Workshop on Positioning Navigation
and Communication (WPNC 2010), 2010, pp. 128–34, doi:10.1109/WPNC.2010.5650745.
short: 'M. Bevermeier, O. Walter, S. Peschke, R. Haeb-Umbach, in: 7th Workshop on
Positioning Navigation and Communication (WPNC 2010), 2010, pp. 128–134.'
date_created: 2019-07-12T05:27:04Z
date_updated: 2022-01-06T06:51:07Z
department:
- _id: '54'
doi: 10.1109/WPNC.2010.5650745
keyword:
- altitude measurement unit
- barometers
- barometric altimeter
- barometric error Kalman filter
- barometric height estimation
- direct cosine matrix
- global positioning system
- Global Positioning System
- GPS device
- height information
- height measurement
- inertial measurement unit
- Kalman filters
- loosely-coupled error state space Kalman filter
- loosely-coupled Kalman-filter
- map matching
- robust information
- robust location estimation
- sensor fusion
- topographic map information
- vertical user position
language:
- iso: eng
main_file_link:
- open_access: '1'
url: https://groups.uni-paderborn.de/nt/pubs/2010/BeWaPeHa10.pdf
oa: '1'
page: 128-134
publication: 7th Workshop on Positioning Navigation and Communication (WPNC 2010)
status: public
title: Barometric height estimation combined with map-matching in a loosely-coupled
Kalman-filter
type: conference
user_id: '44006'
year: '2010'
...
---
_id: '11723'
abstract:
- lang: eng
text: In this paper we present a novel vehicle tracking algorithm, which is based
on multi-level sensor fusion of GPS (global positioning system) with Inertial
Measurement Unit sensor data. It is shown that the robustness of the system to
temporary dropouts of the GPS signal, which may occur due to limited visibility
of satellites in narrow street canyons or tunnels, is greatly improved by sensor
fusion. We further demonstrate how the observation and state noise covariances
of the employed Kalman filters can be estimated alongside the filtering by an
application of the Expectation-Maximization algorithm. The proposed time-variant
multi-level Kalman filter is shown to outperform an Interacting Multiple Model
approach while at the same time being computationally less demanding.
author:
- first_name: Maik
full_name: Bevermeier, Maik
last_name: Bevermeier
- first_name: Sven
full_name: Peschke, Sven
last_name: Peschke
- first_name: Reinhold
full_name: Haeb-Umbach, Reinhold
id: '242'
last_name: Haeb-Umbach
citation:
ama: 'Bevermeier M, Peschke S, Haeb-Umbach R. Robust vehicle localization based
on multi-level sensor fusion and online parameter estimation. In: 6th Workshop
on Positioning Navigation and Communication (WPNC 2009). ; 2009:235-242. doi:10.1109/WPNC.2009.4907833'
apa: Bevermeier, M., Peschke, S., & Haeb-Umbach, R. (2009). Robust vehicle localization
based on multi-level sensor fusion and online parameter estimation. In 6th
Workshop on Positioning Navigation and Communication (WPNC 2009) (pp. 235–242).
https://doi.org/10.1109/WPNC.2009.4907833
bibtex: '@inproceedings{Bevermeier_Peschke_Haeb-Umbach_2009, title={Robust vehicle
localization based on multi-level sensor fusion and online parameter estimation},
DOI={10.1109/WPNC.2009.4907833},
booktitle={6th Workshop on Positioning Navigation and Communication (WPNC 2009)},
author={Bevermeier, Maik and Peschke, Sven and Haeb-Umbach, Reinhold}, year={2009},
pages={235–242} }'
chicago: Bevermeier, Maik, Sven Peschke, and Reinhold Haeb-Umbach. “Robust Vehicle
Localization Based on Multi-Level Sensor Fusion and Online Parameter Estimation.”
In 6th Workshop on Positioning Navigation and Communication (WPNC 2009),
235–42, 2009. https://doi.org/10.1109/WPNC.2009.4907833.
ieee: M. Bevermeier, S. Peschke, and R. Haeb-Umbach, “Robust vehicle localization
based on multi-level sensor fusion and online parameter estimation,” in 6th
Workshop on Positioning Navigation and Communication (WPNC 2009), 2009, pp.
235–242.
mla: Bevermeier, Maik, et al. “Robust Vehicle Localization Based on Multi-Level
Sensor Fusion and Online Parameter Estimation.” 6th Workshop on Positioning
Navigation and Communication (WPNC 2009), 2009, pp. 235–42, doi:10.1109/WPNC.2009.4907833.
short: 'M. Bevermeier, S. Peschke, R. Haeb-Umbach, in: 6th Workshop on Positioning
Navigation and Communication (WPNC 2009), 2009, pp. 235–242.'
date_created: 2019-07-12T05:27:01Z
date_updated: 2022-01-06T06:51:07Z
department:
- _id: '54'
doi: 10.1109/WPNC.2009.4907833
keyword:
- covariance matrices
- expectation-maximisation algorithm
- expectation-maximization algorithm
- global positioning system
- Global Positioning System
- GPS
- inertial measurement unit
- interacting multiple model approach
- Kalman filters
- multilevel sensor fusion
- narrow street canyons
- narrow tunnels
- online parameter estimation
- parameter estimation
- road vehicles
- robust vehicle localization
- sensor fusion
- state noise covariances
- time-variant multilevel Kalman filter
- vehicle tracking algorithm
language:
- iso: eng
main_file_link:
- open_access: '1'
url: https://groups.uni-paderborn.de/nt/pubs/2009/BePeHa09.pdf
oa: '1'
page: 235-242
publication: 6th Workshop on Positioning Navigation and Communication (WPNC 2009)
status: public
title: Robust vehicle localization based on multi-level sensor fusion and online parameter
estimation
type: conference
user_id: '44006'
year: '2009'
...
---
_id: '11938'
abstract:
- lang: eng
text: In this paper, parameter estimation of a state-space model of noise or noisy
speech cepstra is investigated. A blockwise EM algorithm is derived for the estimation
of the state and observation noise covariance from noise-only input data. It is
supposed to be used during the offline training mode of a speech recognizer. Further
a sequential online EM algorithm is developed to adapt the observation noise covariance
on noisy speech cepstra at its input. The estimated parameters are then used in
model-based speech feature enhancement for noise-robust automatic speech recognition.
Experiments on the AURORA4 database lead to improved recognition results with
a linear state model compared to the assumption of stationary noise.
author:
- first_name: Stefan
full_name: Windmann, Stefan
last_name: Windmann
- first_name: Reinhold
full_name: Haeb-Umbach, Reinhold
id: '242'
last_name: Haeb-Umbach
citation:
ama: Windmann S, Haeb-Umbach R. Parameter Estimation of a State-Space Model of Noise
for Robust Speech Recognition. IEEE Transactions on Audio, Speech, and Language
Processing. 2009;17(8):1577-1590. doi:10.1109/TASL.2009.2023172
apa: Windmann, S., & Haeb-Umbach, R. (2009). Parameter Estimation of a State-Space
Model of Noise for Robust Speech Recognition. IEEE Transactions on Audio, Speech,
and Language Processing, 17(8), 1577–1590. https://doi.org/10.1109/TASL.2009.2023172
bibtex: '@article{Windmann_Haeb-Umbach_2009, title={Parameter Estimation of a State-Space
Model of Noise for Robust Speech Recognition}, volume={17}, DOI={10.1109/TASL.2009.2023172},
number={8}, journal={IEEE Transactions on Audio, Speech, and Language Processing},
author={Windmann, Stefan and Haeb-Umbach, Reinhold}, year={2009}, pages={1577–1590}
}'
chicago: 'Windmann, Stefan, and Reinhold Haeb-Umbach. “Parameter Estimation of a
State-Space Model of Noise for Robust Speech Recognition.” IEEE Transactions
on Audio, Speech, and Language Processing 17, no. 8 (2009): 1577–90. https://doi.org/10.1109/TASL.2009.2023172.'
ieee: S. Windmann and R. Haeb-Umbach, “Parameter Estimation of a State-Space Model
of Noise for Robust Speech Recognition,” IEEE Transactions on Audio, Speech,
and Language Processing, vol. 17, no. 8, pp. 1577–1590, 2009.
mla: Windmann, Stefan, and Reinhold Haeb-Umbach. “Parameter Estimation of a State-Space
Model of Noise for Robust Speech Recognition.” IEEE Transactions on Audio,
Speech, and Language Processing, vol. 17, no. 8, 2009, pp. 1577–90, doi:10.1109/TASL.2009.2023172.
short: S. Windmann, R. Haeb-Umbach, IEEE Transactions on Audio, Speech, and Language
Processing 17 (2009) 1577–1590.
date_created: 2019-07-12T05:31:09Z
date_updated: 2022-01-06T06:51:12Z
department:
- _id: '54'
doi: 10.1109/TASL.2009.2023172
intvolume: ' 17'
issue: '8'
keyword:
- AURORA4 database
- blockwise EM algorithm
- covariance analysis
- linear state model
- noise covariance
- noise-robust automatic speech recognition
- noisy speech cepstra
- offline training mode
- parameter estimation
- speech recognition
- speech recognition equipment
- speech recognizer
- state-space methods
- state-space model
language:
- iso: eng
main_file_link:
- open_access: '1'
url: https://groups.uni-paderborn.de/nt/pubs/2009/WiHa09-2.pdf
oa: '1'
page: 1577-1590
publication: IEEE Transactions on Audio, Speech, and Language Processing
status: public
title: Parameter Estimation of a State-Space Model of Noise for Robust Speech Recognition
type: journal_article
user_id: '44006'
volume: 17
year: '2009'
...
---
_id: '11939'
abstract:
- lang: eng
text: In this paper a switching linear dynamical model (SLDM) approach for speech
feature enhancement is improved by employing more accurate models for the dynamics
of speech and noise. The model of the clean speech feature trajectory is improved
by augmenting the state vector to capture information derived from the delta features.
Further a hidden noise state variable is introduced to obtain a more elaborated
model for the noise dynamics. Approximate Bayesian inference in the SLDM is carried
out by a bank of extended Kalman filters, whose outputs are combined according
to the a posteriori probability of the individual state models. Experimental results
on the AURORA2 database show improved recognition accuracy.
author:
- first_name: Stefan
full_name: Windmann, Stefan
last_name: Windmann
- first_name: Reinhold
full_name: Haeb-Umbach, Reinhold
id: '242'
last_name: Haeb-Umbach
citation:
ama: 'Windmann S, Haeb-Umbach R. Modeling the dynamics of speech and noise for speech
feature enhancement in ASR. In: IEEE International Conference on Acoustics,
Speech and Signal Processing (ICASSP 2008). ; 2008:4409-4412. doi:10.1109/ICASSP.2008.4518633'
apa: Windmann, S., & Haeb-Umbach, R. (2008). Modeling the dynamics of speech
and noise for speech feature enhancement in ASR. In IEEE International Conference
on Acoustics, Speech and Signal Processing (ICASSP 2008) (pp. 4409–4412).
https://doi.org/10.1109/ICASSP.2008.4518633
bibtex: '@inproceedings{Windmann_Haeb-Umbach_2008, title={Modeling the dynamics
of speech and noise for speech feature enhancement in ASR}, DOI={10.1109/ICASSP.2008.4518633},
booktitle={IEEE International Conference on Acoustics, Speech and Signal Processing
(ICASSP 2008)}, author={Windmann, Stefan and Haeb-Umbach, Reinhold}, year={2008},
pages={4409–4412} }'
chicago: Windmann, Stefan, and Reinhold Haeb-Umbach. “Modeling the Dynamics of Speech
and Noise for Speech Feature Enhancement in ASR.” In IEEE International Conference
on Acoustics, Speech and Signal Processing (ICASSP 2008), 4409–12, 2008. https://doi.org/10.1109/ICASSP.2008.4518633.
ieee: S. Windmann and R. Haeb-Umbach, “Modeling the dynamics of speech and noise
for speech feature enhancement in ASR,” in IEEE International Conference on
Acoustics, Speech and Signal Processing (ICASSP 2008), 2008, pp. 4409–4412.
mla: Windmann, Stefan, and Reinhold Haeb-Umbach. “Modeling the Dynamics of Speech
and Noise for Speech Feature Enhancement in ASR.” IEEE International Conference
on Acoustics, Speech and Signal Processing (ICASSP 2008), 2008, pp. 4409–12,
doi:10.1109/ICASSP.2008.4518633.
short: 'S. Windmann, R. Haeb-Umbach, in: IEEE International Conference on Acoustics,
Speech and Signal Processing (ICASSP 2008), 2008, pp. 4409–4412.'
date_created: 2019-07-12T05:31:11Z
date_updated: 2022-01-06T06:51:12Z
department:
- _id: '54'
doi: 10.1109/ICASSP.2008.4518633
keyword:
- a posteriori probability
- AURORA2 database
- Bayesian inference
- Bayes methods
- channel bank filters
- extended Kalman filter banks
- hidden noise state variable
- Kalman filters
- noise dynamics
- speech enhancement
- speech feature enhancement
- speech feature trajectory
- switching linear dynamical model approach
language:
- iso: eng
main_file_link:
- open_access: '1'
url: https://groups.uni-paderborn.de/nt/pubs/2008/WiHa08-1.pdf
oa: '1'
page: 4409-4412
publication: IEEE International Conference on Acoustics, Speech and Signal Processing
(ICASSP 2008)
status: public
title: Modeling the dynamics of speech and noise for speech feature enhancement in
ASR
type: conference
user_id: '44006'
year: '2008'
...
---
_id: '11943'
abstract:
- lang: eng
text: A marginalized particle filter is proposed for performing single channel speech
enhancement with a non-linear dynamic state model. The system consists of a particle
filter for tracking line spectral pair (LSP) parameters and a Kalman filter per
particle for speech enhancement. The state model for the LSPs has been learnt
on clean speech training data. In our approach parameters and speech samples are
processed at different time scales by assuming the parameters to be constant for
small blocks of data. Further enhancement is obtained by an iteration which can
be applied on these small blocks. The experiments show that similar SNR gains
are obtained as with the Kalman-LM-iterative algorithm. However better values
of the noise level and the log-spectral distance are achieved
author:
- first_name: Stefan
full_name: Windmann, Stefan
last_name: Windmann
- first_name: Reinhold
full_name: Haeb-Umbach, Reinhold
id: '242'
last_name: Haeb-Umbach
citation:
ama: 'Windmann S, Haeb-Umbach R. Iterative Speech Enhancement using a Non-Linear
Dynamic State Model of Speech and its Parameters. In: IEEE International Conference
on Acoustics, Speech and Signal Processing (ICASSP 2006). Vol 1. ; 2006:I.
doi:10.1109/ICASSP.2006.1660058'
apa: Windmann, S., & Haeb-Umbach, R. (2006). Iterative Speech Enhancement using
a Non-Linear Dynamic State Model of Speech and its Parameters. In IEEE International
Conference on Acoustics, Speech and Signal Processing (ICASSP 2006) (Vol.
1, p. I). https://doi.org/10.1109/ICASSP.2006.1660058
bibtex: '@inproceedings{Windmann_Haeb-Umbach_2006, title={Iterative Speech Enhancement
using a Non-Linear Dynamic State Model of Speech and its Parameters}, volume={1},
DOI={10.1109/ICASSP.2006.1660058},
booktitle={IEEE International Conference on Acoustics, Speech and Signal Processing
(ICASSP 2006)}, author={Windmann, Stefan and Haeb-Umbach, Reinhold}, year={2006},
pages={I} }'
chicago: Windmann, Stefan, and Reinhold Haeb-Umbach. “Iterative Speech Enhancement
Using a Non-Linear Dynamic State Model of Speech and Its Parameters.” In IEEE
International Conference on Acoustics, Speech and Signal Processing (ICASSP 2006),
1:I, 2006. https://doi.org/10.1109/ICASSP.2006.1660058.
ieee: S. Windmann and R. Haeb-Umbach, “Iterative Speech Enhancement using a Non-Linear
Dynamic State Model of Speech and its Parameters,” in IEEE International Conference
on Acoustics, Speech and Signal Processing (ICASSP 2006), 2006, vol. 1, p.
I.
mla: Windmann, Stefan, and Reinhold Haeb-Umbach. “Iterative Speech Enhancement Using
a Non-Linear Dynamic State Model of Speech and Its Parameters.” IEEE International
Conference on Acoustics, Speech and Signal Processing (ICASSP 2006), vol.
1, 2006, p. I, doi:10.1109/ICASSP.2006.1660058.
short: 'S. Windmann, R. Haeb-Umbach, in: IEEE International Conference on Acoustics,
Speech and Signal Processing (ICASSP 2006), 2006, p. I.'
date_created: 2019-07-12T05:31:15Z
date_updated: 2022-01-06T06:51:12Z
department:
- _id: '54'
doi: 10.1109/ICASSP.2006.1660058
intvolume: ' 1'
keyword:
- clean speech training data
- iterative methods
- iterative speech enhancement
- Kalman filter
- Kalman filters
- Kalman-LM-iterative algorithm
- line spectral pair parameters
- log-spectral distance
- marginalized particle filter
- noise level
- nonlinear dynamic state speech model
- particle filtering (numerical methods)
- single channel speech enhancement
- SNR gains
- speech enhancement
- speech samples
language:
- iso: eng
main_file_link:
- open_access: '1'
url: https://groups.uni-paderborn.de/nt/pubs/2006/WiHa06-2.pdf
oa: '1'
page: I
publication: IEEE International Conference on Acoustics, Speech and Signal Processing
(ICASSP 2006)
status: public
title: Iterative Speech Enhancement using a Non-Linear Dynamic State Model of Speech
and its Parameters
type: conference
user_id: '44006'
volume: 1
year: '2006'
...
---
_id: '39352'
abstract:
- lang: eng
text: The recently adopted OCL 2.0 specification comes with a formal semantics that
is based on set theory with a notion of an object model and system states. System
states keep the runtime information relevant for the evaluation of OCL expressions.
However, not all new language concepts of OCL 2.0 are already addressed in that
formal semantics. We show how to overcome this by introducing new components to
the object model and system states defining a dynamic semantics of OCL. In order
to give precise rules that determine when the current system state has to be updated
according to a change in the referred UML model, we make use of adequate mathematical
means, namely Abstract State Machines (ASMs). Though our ASM specification also
gives a clear definition for the evaluation of OCL constraints, it leaves sufficient
flexibility for application specific implementations that have to determine when
constraints are to be checked.
author:
- first_name: Stephan
full_name: Flake, Stephan
last_name: Flake
- first_name: Wolfgang
full_name: Müller, Wolfgang
last_name: Müller
citation:
ama: 'Flake S, Müller W. An ASM Definition of the Dynamic OCL 2.0 Semantics. In:
Proceedings of the UML 2004. ; 2004. doi:10.1007/978-3-540-30187-5_17'
apa: Flake, S., & Müller, W. (2004). An ASM Definition of the Dynamic OCL 2.0
Semantics. Proceedings of the UML 2004. https://doi.org/10.1007/978-3-540-30187-5_17
bibtex: '@inproceedings{Flake_Müller_2004, place={Lisbon, Portugal}, title={An ASM
Definition of the Dynamic OCL 2.0 Semantics}, DOI={10.1007/978-3-540-30187-5_17},
booktitle={Proceedings of the UML 2004}, author={Flake, Stephan and Müller, Wolfgang},
year={2004} }'
chicago: Flake, Stephan, and Wolfgang Müller. “An ASM Definition of the Dynamic
OCL 2.0 Semantics.” In Proceedings of the UML 2004. Lisbon, Portugal, 2004.
https://doi.org/10.1007/978-3-540-30187-5_17.
ieee: 'S. Flake and W. Müller, “An ASM Definition of the Dynamic OCL 2.0 Semantics,”
2004, doi: 10.1007/978-3-540-30187-5_17.'
mla: Flake, Stephan, and Wolfgang Müller. “An ASM Definition of the Dynamic OCL
2.0 Semantics.” Proceedings of the UML 2004, 2004, doi:10.1007/978-3-540-30187-5_17.
short: 'S. Flake, W. Müller, in: Proceedings of the UML 2004, Lisbon, Portugal,
2004.'
date_created: 2023-01-24T09:28:53Z
date_updated: 2023-01-24T09:28:58Z
department:
- _id: '672'
doi: 10.1007/978-3-540-30187-5_17
keyword:
- System State Formal Semantic Object Management Group Denotational Semantic Dynamic
Semantic
language:
- iso: eng
place: Lisbon, Portugal
publication: Proceedings of the UML 2004
publication_identifier:
eisbn:
- 978-3-540-30187-5
status: public
title: An ASM Definition of the Dynamic OCL 2.0 Semantics
type: conference
user_id: '5786'
year: '2004'
...