---
_id: '48896'
abstract:
- lang: eng
text: Hardness of Multi-Objective (MO) continuous optimization problems results
from an interplay of various problem characteristics, e. g. the degree of multi-modality.
We present a benchmark study of classical and diversity focused optimizers on
multi-modal MO problems based on automated algorithm configuration. We show the
large effect of the latter and investigate the trade-off between convergence in
objective space and diversity in decision space.
author:
- first_name: Jeroen
full_name: Rook, Jeroen
last_name: Rook
- first_name: Heike
full_name: Trautmann, Heike
last_name: Trautmann
- first_name: Jakob
full_name: Bossek, Jakob
id: '102979'
last_name: Bossek
orcid: 0000-0002-4121-4668
- first_name: Christian
full_name: Grimme, Christian
last_name: Grimme
citation:
ama: 'Rook J, Trautmann H, Bossek J, Grimme C. On the Potential of Automated Algorithm
Configuration on Multi-Modal Multi-Objective Optimization Problems. In: Proceedings
of the Genetic and Evolutionary Computation Conference Companion. GECCO’22.
Association for Computing Machinery; 2022:356–359. doi:10.1145/3520304.3528998'
apa: Rook, J., Trautmann, H., Bossek, J., & Grimme, C. (2022). On the Potential
of Automated Algorithm Configuration on Multi-Modal Multi-Objective Optimization
Problems. Proceedings of the Genetic and Evolutionary Computation Conference
Companion, 356–359. https://doi.org/10.1145/3520304.3528998
bibtex: '@inproceedings{Rook_Trautmann_Bossek_Grimme_2022, place={New York, NY,
USA}, series={GECCO’22}, title={On the Potential of Automated Algorithm Configuration
on Multi-Modal Multi-Objective Optimization Problems}, DOI={10.1145/3520304.3528998},
booktitle={Proceedings of the Genetic and Evolutionary Computation Conference
Companion}, publisher={Association for Computing Machinery}, author={Rook, Jeroen
and Trautmann, Heike and Bossek, Jakob and Grimme, Christian}, year={2022}, pages={356–359},
collection={GECCO’22} }'
chicago: 'Rook, Jeroen, Heike Trautmann, Jakob Bossek, and Christian Grimme. “On
the Potential of Automated Algorithm Configuration on Multi-Modal Multi-Objective
Optimization Problems.” In Proceedings of the Genetic and Evolutionary Computation
Conference Companion, 356–359. GECCO’22. New York, NY, USA: Association for
Computing Machinery, 2022. https://doi.org/10.1145/3520304.3528998.'
ieee: 'J. Rook, H. Trautmann, J. Bossek, and C. Grimme, “On the Potential of Automated
Algorithm Configuration on Multi-Modal Multi-Objective Optimization Problems,”
in Proceedings of the Genetic and Evolutionary Computation Conference Companion,
2022, pp. 356–359, doi: 10.1145/3520304.3528998.'
mla: Rook, Jeroen, et al. “On the Potential of Automated Algorithm Configuration
on Multi-Modal Multi-Objective Optimization Problems.” Proceedings of the Genetic
and Evolutionary Computation Conference Companion, Association for Computing
Machinery, 2022, pp. 356–359, doi:10.1145/3520304.3528998.
short: 'J. Rook, H. Trautmann, J. Bossek, C. Grimme, in: Proceedings of the Genetic
and Evolutionary Computation Conference Companion, Association for Computing Machinery,
New York, NY, USA, 2022, pp. 356–359.'
date_created: 2023-11-14T15:59:00Z
date_updated: 2023-12-13T10:50:24Z
department:
- _id: '819'
doi: 10.1145/3520304.3528998
extern: '1'
keyword:
- configuration
- multi-modality
- multi-objective optimization
language:
- iso: eng
page: 356–359
place: New York, NY, USA
publication: Proceedings of the Genetic and Evolutionary Computation Conference Companion
publication_identifier:
isbn:
- 978-1-4503-9268-6
publisher: Association for Computing Machinery
series_title: GECCO’22
status: public
title: On the Potential of Automated Algorithm Configuration on Multi-Modal Multi-Objective
Optimization Problems
type: conference
user_id: '102979'
year: '2022'
...
---
_id: '21004'
abstract:
- lang: eng
text: 'Automated machine learning (AutoML) supports the algorithmic construction
and data-specific customization of machine learning pipelines, including the selection,
combination, and parametrization of machine learning algorithms as main constituents.
Generally speaking, AutoML approaches comprise two major components: a search
space model and an optimizer for traversing the space. Recent approaches have
shown impressive results in the realm of supervised learning, most notably (single-label)
classification (SLC). Moreover, first attempts at extending these approaches towards
multi-label classification (MLC) have been made. While the space of candidate
pipelines is already huge in SLC, the complexity of the search space is raised
to an even higher power in MLC. One may wonder, therefore, whether and to what
extent optimizers established for SLC can scale to this increased complexity,
and how they compare to each other. This paper makes the following contributions:
First, we survey existing approaches to AutoML for MLC. Second, we augment these
approaches with optimizers not previously tried for MLC. Third, we propose a benchmarking
framework that supports a fair and systematic comparison. Fourth, we conduct an
extensive experimental study, evaluating the methods on a suite of MLC problems.
We find a grammar-based best-first search to compare favorably to other optimizers.'
author:
- first_name: Marcel Dominik
full_name: Wever, Marcel Dominik
id: '33176'
last_name: Wever
orcid: ' https://orcid.org/0000-0001-9782-6818'
- first_name: Alexander
full_name: Tornede, Alexander
id: '38209'
last_name: Tornede
- first_name: Felix
full_name: Mohr, Felix
last_name: Mohr
- first_name: Eyke
full_name: Hüllermeier, Eyke
id: '48129'
last_name: Hüllermeier
citation:
ama: 'Wever MD, Tornede A, Mohr F, Hüllermeier E. AutoML for Multi-Label Classification:
Overview and Empirical Evaluation. IEEE Transactions on Pattern Analysis and
Machine Intelligence. Published online 2021:1-1. doi:10.1109/tpami.2021.3051276'
apa: 'Wever, M. D., Tornede, A., Mohr, F., & Hüllermeier, E. (2021). AutoML
for Multi-Label Classification: Overview and Empirical Evaluation. IEEE Transactions
on Pattern Analysis and Machine Intelligence, 1–1. https://doi.org/10.1109/tpami.2021.3051276'
bibtex: '@article{Wever_Tornede_Mohr_Hüllermeier_2021, title={AutoML for Multi-Label
Classification: Overview and Empirical Evaluation}, DOI={10.1109/tpami.2021.3051276},
journal={IEEE Transactions on Pattern Analysis and Machine Intelligence}, author={Wever,
Marcel Dominik and Tornede, Alexander and Mohr, Felix and Hüllermeier, Eyke},
year={2021}, pages={1–1} }'
chicago: 'Wever, Marcel Dominik, Alexander Tornede, Felix Mohr, and Eyke Hüllermeier.
“AutoML for Multi-Label Classification: Overview and Empirical Evaluation.” IEEE
Transactions on Pattern Analysis and Machine Intelligence, 2021, 1–1. https://doi.org/10.1109/tpami.2021.3051276.'
ieee: 'M. D. Wever, A. Tornede, F. Mohr, and E. Hüllermeier, “AutoML for Multi-Label
Classification: Overview and Empirical Evaluation,” IEEE Transactions on Pattern
Analysis and Machine Intelligence, pp. 1–1, 2021, doi: 10.1109/tpami.2021.3051276.'
mla: 'Wever, Marcel Dominik, et al. “AutoML for Multi-Label Classification: Overview
and Empirical Evaluation.” IEEE Transactions on Pattern Analysis and Machine
Intelligence, 2021, pp. 1–1, doi:10.1109/tpami.2021.3051276.'
short: M.D. Wever, A. Tornede, F. Mohr, E. Hüllermeier, IEEE Transactions on Pattern
Analysis and Machine Intelligence (2021) 1–1.
date_created: 2021-01-16T14:48:13Z
date_updated: 2022-01-06T06:54:42Z
department:
- _id: '34'
- _id: '355'
- _id: '26'
doi: 10.1109/tpami.2021.3051276
keyword:
- Automated Machine Learning
- Multi Label Classification
- Hierarchical Planning
- Bayesian Optimization
language:
- iso: eng
page: 1-1
project:
- _id: '1'
name: SFB 901
- _id: '3'
name: SFB 901 - Project Area B
- _id: '10'
name: SFB 901 - Subproject B2
- _id: '52'
name: Computing Resources Provided by the Paderborn Center for Parallel Computing
publication: IEEE Transactions on Pattern Analysis and Machine Intelligence
publication_identifier:
issn:
- 0162-8828
- 2160-9292
- 1939-3539
publication_status: published
status: public
title: 'AutoML for Multi-Label Classification: Overview and Empirical Evaluation'
type: journal_article
user_id: '5786'
year: '2021'
...
---
_id: '21808'
abstract:
- lang: eng
text: "Modern services consist of interconnected components,e.g., microservices
in a service mesh or machine learning functions in a pipeline. These services
can scale and run across multiple network nodes on demand. To process incoming
traffic, service components have to be instantiated and traffic assigned to these
instances, taking capacities, changing demands, and Quality of Service (QoS) requirements
into account. This challenge is usually solved with custom approaches designed
by experts. While this typically works well for the considered scenario, the models
often rely on unrealistic assumptions or on knowledge that is not available in
practice (e.g., a priori knowledge).\r\n\r\nWe propose DeepCoord, a novel deep
reinforcement learning approach that learns how to best coordinate services and
is geared towards realistic assumptions. It interacts with the network and relies
on available, possibly delayed monitoring information. Rather than defining a
complex model or an algorithm on how to achieve an objective, our model-free approach
adapts to various objectives and traffic patterns. An agent is trained offline
without expert knowledge and then applied online with minimal overhead. Compared
to a state-of-the-art heuristic, DeepCoord significantly improves flow throughput
(up to 76%) and overall network utility (more than 2x) on realworld network topologies
and traffic traces. It also supports optimizing multiple, possibly competing objectives,
learns to respect QoS requirements, generalizes to scenarios with unseen, stochastic
traffic, and scales to large real-world networks. For reproducibility and reuse,
our code is publicly available."
article_type: original
author:
- first_name: Stefan Balthasar
full_name: Schneider, Stefan Balthasar
id: '35343'
last_name: Schneider
orcid: 0000-0001-8210-4011
- first_name: Ramin
full_name: Khalili, Ramin
last_name: Khalili
- first_name: Adnan
full_name: Manzoor, Adnan
last_name: Manzoor
- first_name: Haydar
full_name: Qarawlus, Haydar
last_name: Qarawlus
- first_name: Rafael
full_name: Schellenberg, Rafael
last_name: Schellenberg
- first_name: Holger
full_name: Karl, Holger
id: '126'
last_name: Karl
- first_name: Artur
full_name: Hecker, Artur
last_name: Hecker
citation:
ama: Schneider SB, Khalili R, Manzoor A, et al. Self-Learning Multi-Objective Service
Coordination Using Deep Reinforcement Learning. Transactions on Network and
Service Management. 2021. doi:10.1109/TNSM.2021.3076503
apa: Schneider, S. B., Khalili, R., Manzoor, A., Qarawlus, H., Schellenberg, R.,
Karl, H., & Hecker, A. (2021). Self-Learning Multi-Objective Service Coordination
Using Deep Reinforcement Learning. Transactions on Network and Service Management.
https://doi.org/10.1109/TNSM.2021.3076503
bibtex: '@article{Schneider_Khalili_Manzoor_Qarawlus_Schellenberg_Karl_Hecker_2021,
title={Self-Learning Multi-Objective Service Coordination Using Deep Reinforcement
Learning}, DOI={10.1109/TNSM.2021.3076503},
journal={Transactions on Network and Service Management}, publisher={IEEE}, author={Schneider,
Stefan Balthasar and Khalili, Ramin and Manzoor, Adnan and Qarawlus, Haydar and
Schellenberg, Rafael and Karl, Holger and Hecker, Artur}, year={2021} }'
chicago: Schneider, Stefan Balthasar, Ramin Khalili, Adnan Manzoor, Haydar Qarawlus,
Rafael Schellenberg, Holger Karl, and Artur Hecker. “Self-Learning Multi-Objective
Service Coordination Using Deep Reinforcement Learning.” Transactions on Network
and Service Management, 2021. https://doi.org/10.1109/TNSM.2021.3076503.
ieee: S. B. Schneider et al., “Self-Learning Multi-Objective Service Coordination
Using Deep Reinforcement Learning,” Transactions on Network and Service Management,
2021.
mla: Schneider, Stefan Balthasar, et al. “Self-Learning Multi-Objective Service
Coordination Using Deep Reinforcement Learning.” Transactions on Network and
Service Management, IEEE, 2021, doi:10.1109/TNSM.2021.3076503.
short: S.B. Schneider, R. Khalili, A. Manzoor, H. Qarawlus, R. Schellenberg, H.
Karl, A. Hecker, Transactions on Network and Service Management (2021).
date_created: 2021-04-27T08:04:16Z
date_updated: 2022-01-06T06:55:15Z
ddc:
- '000'
department:
- _id: '75'
doi: 10.1109/TNSM.2021.3076503
file:
- access_level: open_access
content_type: application/pdf
creator: stschn
date_created: 2021-04-27T08:01:26Z
date_updated: 2021-04-27T08:01:26Z
description: Author version of the accepted paper
file_id: '21809'
file_name: ris-accepted-version.pdf
file_size: 4172270
relation: main_file
file_date_updated: 2021-04-27T08:01:26Z
has_accepted_license: '1'
keyword:
- network management
- service management
- coordination
- reinforcement learning
- self-learning
- self-adaptation
- multi-objective
language:
- iso: eng
oa: '1'
project:
- _id: '1'
name: SFB 901
- _id: '4'
name: SFB 901 - Project Area C
- _id: '16'
name: SFB 901 - Subproject C4
publication: Transactions on Network and Service Management
publisher: IEEE
status: public
title: Self-Learning Multi-Objective Service Coordination Using Deep Reinforcement
Learning
type: journal_article
user_id: '35343'
year: '2021'
...
---
_id: '33854'
abstract:
- lang: eng
text: "Macrodiversity is a key technique to increase the capacity of mobile networks.
It can be realized using coordinated multipoint (CoMP), simultaneously connecting
users to multiple overlapping cells. Selecting which users to serve by how many
and which cells is NP-hard but needs to happen continuously in real time as users
move and channel state changes. Existing approaches often require strict assumptions
about or perfect knowledge of the underlying radio system, its resource allocation
scheme, or user movements, none of which is readily available in practice.\r\n\r\nInstead,
we propose three novel self-learning and self-adapting approaches using model-free
deep reinforcement learning (DRL): DeepCoMP, DD-CoMP, and D3-CoMP. DeepCoMP leverages
central observations and control of all users to select cells almost optimally.
DD-CoMP and D3-CoMP use multi-agent DRL, which allows distributed, robust, and
highly scalable coordination. All three approaches learn from experience and self-adapt
to varying scenarios, reaching 2x higher Quality of Experience than other approaches.
They have very few built-in assumptions and do not need prior system knowledge,
making them more robust to change and better applicable in practice than existing
approaches."
author:
- first_name: Stefan Balthasar
full_name: Schneider, Stefan Balthasar
id: '35343'
last_name: Schneider
orcid: 0000-0001-8210-4011
- first_name: Holger
full_name: Karl, Holger
id: '126'
last_name: Karl
- first_name: Ramin
full_name: Khalili, Ramin
last_name: Khalili
- first_name: Artur
full_name: Hecker, Artur
last_name: Hecker
citation:
ama: 'Schneider SB, Karl H, Khalili R, Hecker A. DeepCoMP: Coordinated Multipoint
Using Multi-Agent Deep Reinforcement Learning.; 2021.'
apa: 'Schneider, S. B., Karl, H., Khalili, R., & Hecker, A. (2021). DeepCoMP:
Coordinated Multipoint Using Multi-Agent Deep Reinforcement Learning.'
bibtex: '@book{Schneider_Karl_Khalili_Hecker_2021, title={DeepCoMP: Coordinated
Multipoint Using Multi-Agent Deep Reinforcement Learning}, author={Schneider,
Stefan Balthasar and Karl, Holger and Khalili, Ramin and Hecker, Artur}, year={2021}
}'
chicago: 'Schneider, Stefan Balthasar, Holger Karl, Ramin Khalili, and Artur Hecker.
DeepCoMP: Coordinated Multipoint Using Multi-Agent Deep Reinforcement Learning,
2021.'
ieee: 'S. B. Schneider, H. Karl, R. Khalili, and A. Hecker, DeepCoMP: Coordinated
Multipoint Using Multi-Agent Deep Reinforcement Learning. 2021.'
mla: 'Schneider, Stefan Balthasar, et al. DeepCoMP: Coordinated Multipoint Using
Multi-Agent Deep Reinforcement Learning. 2021.'
short: 'S.B. Schneider, H. Karl, R. Khalili, A. Hecker, DeepCoMP: Coordinated Multipoint
Using Multi-Agent Deep Reinforcement Learning, 2021.'
date_created: 2022-10-20T16:44:19Z
date_updated: 2022-11-18T09:59:27Z
ddc:
- '004'
department:
- _id: '75'
file:
- access_level: open_access
content_type: application/pdf
creator: stschn
date_created: 2022-10-20T16:41:10Z
date_updated: 2022-10-20T16:41:10Z
file_id: '33855'
file_name: preprint.pdf
file_size: 2521656
relation: main_file
file_date_updated: 2022-10-20T16:41:10Z
has_accepted_license: '1'
keyword:
- mobility management
- coordinated multipoint
- CoMP
- cell selection
- resource management
- reinforcement learning
- multi agent
- MARL
- self-learning
- self-adaptation
- QoE
language:
- iso: eng
oa: '1'
project:
- _id: '4'
name: 'SFB 901 - C: SFB 901 - Project Area C'
- _id: '16'
name: 'SFB 901 - C4: SFB 901 - Subproject C4'
- _id: '1'
name: 'SFB 901: SFB 901'
status: public
title: 'DeepCoMP: Coordinated Multipoint Using Multi-Agent Deep Reinforcement Learning'
type: working_paper
user_id: '477'
year: '2021'
...
---
_id: '32558'
abstract:
- lang: eng
text: With the rapid progress of technological development, self-efficacy in reference
to digital devices (i.e., information and computer technology [ICT] self-efficacy)
is an important driver that helps students to deal with technological problems
and support their lifelong learning processes. Schools, peers, and home learning
environments are important sources for the development of positive self-efficacy.
Expanding on previous research, we investigated the associations between different
aspects of the digital home learning environment and students’ ICT self-efficacy.
The moderation effects of gender were also tested. A total of 651 children answered
a questionnaire about different digital home learning environment dimensions and
estimated their ICT self-efficacy using an adapted scale—Schwarzer and Jerusalem’s
(1999) general self-efficacy scale. Using the structural equation modeling technique,
a digital home learning environment containing six different qualities of parental
support was investigated. Families’ cultural capital, parents’ attitudes toward
the Internet, and shared Internet activities at home contributed positively to
ICT self-efficacy. We observed small gender differences, with the moderation effect
being nonsignificant. The results help researchers and practitioners to understand
how different dimensions of the digital home learning environment support ICT
self-efficacy. We will discuss how parents can enhance the home learning environment
and how teachers can integrate this knowledge into formal education.
author:
- first_name: Sabrina
full_name: Bonanati, Sabrina
last_name: Bonanati
- first_name: Heike M.
full_name: Buhl, Heike M.
id: '27152'
last_name: Buhl
citation:
ama: Bonanati S, Buhl HM. The digital home learning environment and its relation
to children’s ICT self-efficacy. Learning Environments Research. 2021;25(2):485-505.
doi:10.1007/s10984-021-09377-8
apa: Bonanati, S., & Buhl, H. M. (2021). The digital home learning environment
and its relation to children’s ICT self-efficacy. Learning Environments Research,
25(2), 485–505. https://doi.org/10.1007/s10984-021-09377-8
bibtex: '@article{Bonanati_Buhl_2021, title={The digital home learning environment
and its relation to children’s ICT self-efficacy}, volume={25}, DOI={10.1007/s10984-021-09377-8},
number={2}, journal={Learning Environments Research}, publisher={Springer Science
and Business Media LLC}, author={Bonanati, Sabrina and Buhl, Heike M.}, year={2021},
pages={485–505} }'
chicago: 'Bonanati, Sabrina, and Heike M. Buhl. “The Digital Home Learning Environment
and Its Relation to Children’s ICT Self-Efficacy.” Learning Environments Research
25, no. 2 (2021): 485–505. https://doi.org/10.1007/s10984-021-09377-8.'
ieee: 'S. Bonanati and H. M. Buhl, “The digital home learning environment and its
relation to children’s ICT self-efficacy,” Learning Environments Research,
vol. 25, no. 2, pp. 485–505, 2021, doi: 10.1007/s10984-021-09377-8.'
mla: Bonanati, Sabrina, and Heike M. Buhl. “The Digital Home Learning Environment
and Its Relation to Children’s ICT Self-Efficacy.” Learning Environments Research,
vol. 25, no. 2, Springer Science and Business Media LLC, 2021, pp. 485–505, doi:10.1007/s10984-021-09377-8.
short: S. Bonanati, H.M. Buhl, Learning Environments Research 25 (2021) 485–505.
date_created: 2022-08-03T05:53:48Z
date_updated: 2022-08-29T06:36:37Z
department:
- _id: '427'
doi: 10.1007/s10984-021-09377-8
intvolume: ' 25'
issue: '2'
keyword:
- Digital media use
- Gender
- Home learning environment
- ICT self-efcacy
- Motivation
- Parental involvement
language:
- iso: eng
main_file_link:
- open_access: '1'
url: https://link.springer.com/content/pdf/10.1007/s10984-021-09377-8.pdf
oa: '1'
page: 485-505
publication: Learning Environments Research
publication_identifier:
issn:
- 1387-1579
- 1573-1855
publication_status: published
publisher: Springer Science and Business Media LLC
status: public
title: The digital home learning environment and its relation to children’s ICT self-efficacy
type: journal_article
user_id: '42165'
volume: 25
year: '2021'
...
---
_id: '37136'
abstract:
- lang: eng
text: This study examines the relation between voluntary audit and the cost of debt
in private firms. We use a sample of 4,058 small private firms operating in the
period 2006‐2017 that are not subject to mandatory audits. Firms decide for a
voluntary audit of financial statements either because the economic setting in
which they operate effectively forces them to do so (e.g., ownership complexity,
export‐oriented supply chain, subsidiary status) or because firm fundamentals
and/or financial reporting practices limit their access to financial debt, both
reflected in earnings quality. We use these factors to model the decision for
voluntary audit. In the outcome analyses, we find robust evidence that voluntary
audits are associated with higher, rather than lower, interest rate by up to 3.0
percentage points. This effect is present regardless of the perceived audit quality
(Big‐4 vs. non‐Big‐4), but is stronger for non‐Big‐4 audits where auditees have
a stronger position relative to auditors. Audited firms’ earnings are less informative
about future operating performance relative to unaudited counterparts. We conclude
that voluntary audits facilitate access to financial debt for firms with higher
risk that may otherwise have no access to this form of financing. The price paid
is reflected in higher interest rates charged to firms with voluntary audits –
firms with higher information and/or fundamental risk.
author:
- first_name: Riste
full_name: Ichev, Riste
last_name: Ichev
- first_name: Jernej
full_name: Koren, Jernej
last_name: Koren
- first_name: Urska
full_name: Kosi, Urska
id: '54068'
last_name: Kosi
- first_name: Katarina
full_name: Sitar Sustar, Katarina
last_name: Sitar Sustar
- first_name: Aljosa
full_name: Valentincic, Aljosa
last_name: Valentincic
citation:
ama: 'Ichev R, Koren J, Kosi U, Sitar Sustar K, Valentincic A. Cost of Debt for
Private Firms Revisited: Voluntary Audits as a Reflection of Risk.; 2021.'
apa: 'Ichev, R., Koren, J., Kosi, U., Sitar Sustar, K., & Valentincic, A. (2021).
Cost of Debt for Private Firms Revisited: Voluntary Audits as a Reflection
of Risk.'
bibtex: '@book{Ichev_Koren_Kosi_Sitar Sustar_Valentincic_2021, title={Cost of Debt
for Private Firms Revisited: Voluntary Audits as a Reflection of Risk}, author={Ichev,
Riste and Koren, Jernej and Kosi, Urska and Sitar Sustar, Katarina and Valentincic,
Aljosa}, year={2021} }'
chicago: 'Ichev, Riste, Jernej Koren, Urska Kosi, Katarina Sitar Sustar, and Aljosa
Valentincic. Cost of Debt for Private Firms Revisited: Voluntary Audits as
a Reflection of Risk, 2021.'
ieee: 'R. Ichev, J. Koren, U. Kosi, K. Sitar Sustar, and A. Valentincic, Cost
of Debt for Private Firms Revisited: Voluntary Audits as a Reflection of Risk.
2021.'
mla: 'Ichev, Riste, et al. Cost of Debt for Private Firms Revisited: Voluntary
Audits as a Reflection of Risk. 2021.'
short: 'R. Ichev, J. Koren, U. Kosi, K. Sitar Sustar, A. Valentincic, Cost of Debt
for Private Firms Revisited: Voluntary Audits as a Reflection of Risk, 2021.'
date_created: 2023-01-17T15:03:08Z
date_updated: 2023-01-18T13:40:40Z
department:
- _id: '635'
- _id: '186'
- _id: '551'
keyword:
- private firms
- voluntary audit
- cost of debt
- self‐selection bias
- risk
language:
- iso: eng
main_file_link:
- url: https://papers.ssrn.com/sol3/papers.cfm?abstract_id=3853927
status: public
title: 'Cost of Debt for Private Firms Revisited: Voluntary Audits as a Reflection
of Risk'
type: working_paper
user_id: '88603'
year: '2021'
...
---
_id: '22930'
abstract:
- lang: eng
text: Self-piercing riveting is an established technique for joining multi-material
structures in car body manufacturing. Rivets for self-piercing riveting differ
in their geometry, the material used, the condition of the material and their
surface condition. To shorten the manufacturing process by omitting the heat treatment
and the coating process, the authors have elaborated a concept for the use of
stainless steel with high strain hardening as a rivet material. The focus of the
present investigation is on the evaluation of the influences of the rivet’s geometry
and material on its deformation behaviour. Conventional rivets of types P and
HD2, a rivet with an improved geometry made of treatable steel 38B2, and rivets
made of the stainless steels 1.3815 and 1.4541 are examined. The analysis is conducted
by means of multi-step joining tests for two material combinations comprising
high-strength steel HCT70X and aluminium EN AW-5083. The joints are cut to provide
a cross-section and the deformation behaviour of the different rivets is analysed
on the basis of the measured changes in geometry and hardness. In parallel, an
examination of the force-stroke curves provides further insights. It can be demonstrated
that, besides the geometry, the material strength, in particular, has a significant
influence on the deformation behaviour of the rivet. The strength of steel 1.4541
is seen to be too low for the joining task, while the strength of steel 1.3815
is sufficient, and hence the investigation confirms the capability of rivets made
of 1.3815 for joining even challenging material combinations.
author:
- first_name: Benedikt
full_name: Uhe, Benedikt
id: '38131'
last_name: Uhe
- first_name: Clara-Maria
full_name: Kuball, Clara-Maria
last_name: Kuball
- first_name: Marion
full_name: Merklein, Marion
last_name: Merklein
- first_name: Gerson
full_name: Meschut, Gerson
id: '32056'
last_name: Meschut
orcid: 0000-0002-2763-1246
citation:
ama: 'Uhe B, Kuball C-M, Merklein M, Meschut G. Self-Piercing Riveting Using Rivets
Made of Stainless Steel with High Strain Hardening. In: Daehn G, Cao J, Kinsey
B, Tekkaya E, Vivek A, Yoshida Y, eds. Forming the Future - Proceedings of
the 13th International Conference on the Technology of Plasticity. The Minerals,
Metals & Materials Series. Springer; 2021:1495-1506. doi:10.1007/978-3-030-75381-8_124'
apa: Uhe, B., Kuball, C.-M., Merklein, M., & Meschut, G. (2021). Self-Piercing
Riveting Using Rivets Made of Stainless Steel with High Strain Hardening. In G.
Daehn, J. Cao, B. Kinsey, E. Tekkaya, A. Vivek, & Y. Yoshida (Eds.), Forming
the Future - Proceedings of the 13th International Conference on the Technology
of Plasticity. The Minerals, Metals & Materials Series. (pp. 1495–1506).
Springer. https://doi.org/10.1007/978-3-030-75381-8_124
bibtex: '@inbook{Uhe_Kuball_Merklein_Meschut_2021, place={Cham}, title={Self-Piercing
Riveting Using Rivets Made of Stainless Steel with High Strain Hardening}, DOI={10.1007/978-3-030-75381-8_124},
booktitle={Forming the Future - Proceedings of the 13th International Conference
on the Technology of Plasticity. The Minerals, Metals & Materials Series.},
publisher={Springer}, author={Uhe, Benedikt and Kuball, Clara-Maria and Merklein,
Marion and Meschut, Gerson}, editor={Daehn, Glenn and Cao, Jian and Kinsey, Brad
and Tekkaya, Erman and Vivek, Anupam and Yoshida, Yoshinori}, year={2021}, pages={1495–1506}
}'
chicago: 'Uhe, Benedikt, Clara-Maria Kuball, Marion Merklein, and Gerson Meschut.
“Self-Piercing Riveting Using Rivets Made of Stainless Steel with High Strain
Hardening.” In Forming the Future - Proceedings of the 13th International Conference
on the Technology of Plasticity. The Minerals, Metals & Materials Series.,
edited by Glenn Daehn, Jian Cao, Brad Kinsey, Erman Tekkaya, Anupam Vivek, and
Yoshinori Yoshida, 1495–1506. Cham: Springer, 2021. https://doi.org/10.1007/978-3-030-75381-8_124.'
ieee: 'B. Uhe, C.-M. Kuball, M. Merklein, and G. Meschut, “Self-Piercing Riveting
Using Rivets Made of Stainless Steel with High Strain Hardening,” in Forming
the Future - Proceedings of the 13th International Conference on the Technology
of Plasticity. The Minerals, Metals & Materials Series., G. Daehn, J.
Cao, B. Kinsey, E. Tekkaya, A. Vivek, and Y. Yoshida, Eds. Cham: Springer, 2021,
pp. 1495–1506.'
mla: Uhe, Benedikt, et al. “Self-Piercing Riveting Using Rivets Made of Stainless
Steel with High Strain Hardening.” Forming the Future - Proceedings of the
13th International Conference on the Technology of Plasticity. The Minerals, Metals
& Materials Series., edited by Glenn Daehn et al., Springer, 2021, pp.
1495–506, doi:10.1007/978-3-030-75381-8_124.
short: 'B. Uhe, C.-M. Kuball, M. Merklein, G. Meschut, in: G. Daehn, J. Cao, B.
Kinsey, E. Tekkaya, A. Vivek, Y. Yoshida (Eds.), Forming the Future - Proceedings
of the 13th International Conference on the Technology of Plasticity. The Minerals,
Metals & Materials Series., Springer, Cham, 2021, pp. 1495–1506.'
date_created: 2021-08-04T14:02:32Z
date_updated: 2023-04-28T09:20:35Z
department:
- _id: '157'
doi: 10.1007/978-3-030-75381-8_124
editor:
- first_name: Glenn
full_name: Daehn, Glenn
last_name: Daehn
- first_name: Jian
full_name: Cao, Jian
last_name: Cao
- first_name: Brad
full_name: Kinsey, Brad
last_name: Kinsey
- first_name: Erman
full_name: Tekkaya, Erman
last_name: Tekkaya
- first_name: Anupam
full_name: Vivek, Anupam
last_name: Vivek
- first_name: Yoshinori
full_name: Yoshida, Yoshinori
last_name: Yoshida
keyword:
- Self-piercing riveting
- Lightweight design
- Deformation behaviour
- Stainless steel
- High nitrogen steel
language:
- iso: eng
page: 1495-1506
place: Cham
publication: Forming the Future - Proceedings of the 13th International Conference
on the Technology of Plasticity. The Minerals, Metals & Materials Series.
publication_status: published
publisher: Springer
quality_controlled: '1'
status: public
title: Self-Piercing Riveting Using Rivets Made of Stainless Steel with High Strain
Hardening
type: book_chapter
user_id: '38131'
year: '2021'
...
---
_id: '22274'
abstract:
- lang: eng
text: 'The use of high-strength steel and aluminium is rising due to the intensified
efforts being made in lightweight design, and self-piercing riveting is becoming
increasingly important. Conventional rivets for self-piercing riveting differ
in their geometry, the material used, the condition of the material and the coating.
To shorten the manufacturing process, the use of stainless steel with high strain
hardening as the rivet material represents a promising approach. This allows the
coating of the rivets to be omitted due to the corrosion resistance of the material
and, since the strength of the stainless steel is achieved by cold forming, heat
treatment is no longer required. In addition, it is possible to adjust the local
strength within the rivet. Because of that, the authors have elaborated a concept
for using high nitrogen steel 1.3815 as the rivet material. The present investigation
focusses on the joint strength in order to evaluate the capability of rivets in
high nitrogen steel by comparison to conventional rivets made of treatable steel.
Due to certain challenges in the forming process of the high nitrogen steel rivets,
deviations result from the targeted rivet geometry. Mainly these deviations cause
a lower joint strength with these rivets, which is, however, adequate. All in
all, the capability of the new rivet is proven by the results of this investigation. '
author:
- first_name: Benedikt
full_name: Uhe, Benedikt
id: '38131'
last_name: Uhe
- first_name: Clara-Maria
full_name: Kuball, Clara-Maria
last_name: Kuball
- first_name: Marion
full_name: Merklein, Marion
last_name: Merklein
- first_name: Gerson
full_name: Meschut, Gerson
id: '32056'
last_name: Meschut
orcid: 0000-0002-2763-1246
citation:
ama: 'Uhe B, Kuball C-M, Merklein M, Meschut G. Strength of self-piercing riveted
Joints with conventional Rivets and Rivets made of High Nitrogen Steel. In: ;
2021. doi:10.25518/esaform21.1911'
apa: Uhe, B., Kuball, C.-M., Merklein, M., & Meschut, G. (2021). Strength
of self-piercing riveted Joints with conventional Rivets and Rivets made of High
Nitrogen Steel. 24th International Conference on Material Forming (ESAFORM),
Liège, Belgien. https://doi.org/10.25518/esaform21.1911
bibtex: '@inproceedings{Uhe_Kuball_Merklein_Meschut_2021, title={Strength of self-piercing
riveted Joints with conventional Rivets and Rivets made of High Nitrogen Steel},
DOI={10.25518/esaform21.1911},
author={Uhe, Benedikt and Kuball, Clara-Maria and Merklein, Marion and Meschut,
Gerson}, year={2021} }'
chicago: Uhe, Benedikt, Clara-Maria Kuball, Marion Merklein, and Gerson Meschut.
“Strength of Self-Piercing Riveted Joints with Conventional Rivets and Rivets
Made of High Nitrogen Steel,” 2021. https://doi.org/10.25518/esaform21.1911.
ieee: 'B. Uhe, C.-M. Kuball, M. Merklein, and G. Meschut, “Strength of self-piercing
riveted Joints with conventional Rivets and Rivets made of High Nitrogen Steel,”
presented at the 24th International Conference on Material Forming (ESAFORM),
Liège, Belgien, 2021, doi: 10.25518/esaform21.1911.'
mla: Uhe, Benedikt, et al. Strength of Self-Piercing Riveted Joints with Conventional
Rivets and Rivets Made of High Nitrogen Steel. 2021, doi:10.25518/esaform21.1911.
short: 'B. Uhe, C.-M. Kuball, M. Merklein, G. Meschut, in: 2021.'
conference:
end_date: 2021-04-16
location: Liège, Belgien
name: 24th International Conference on Material Forming (ESAFORM)
start_date: 2021-04-14
date_created: 2021-05-31T10:17:37Z
date_updated: 2023-04-28T09:20:05Z
department:
- _id: '157'
doi: 10.25518/esaform21.1911
keyword:
- Self-piercing Riveting
- Joining Technology
- Rivet Geometry
- Rivet Material
- High Nitrogen Steel
- Joint Strength
language:
- iso: eng
quality_controlled: '1'
status: public
title: Strength of self-piercing riveted Joints with conventional Rivets and Rivets
made of High Nitrogen Steel
type: conference
user_id: '38131'
year: '2021'
...
---
_id: '21436'
abstract:
- lang: eng
text: Ultrasonic wire bonding is a solid-state joining process, used in the electronics
industry to form electrical connections, e.g. to connect electrical terminals
within semiconductor modules. Many process parameters affect the bond strength,
such like the bond normal force, ultrasonic power, wire material and bonding frequency.
Today, process design, development, and optimization is most likely based on the
knowledge of process engineers and is mainly performed by experimental testing.
In this contribution, a newly developed simulation tool is presented, to reduce
time and costs and efficiently determine optimized process parameter. Based on
a co-simulation of MATLAB and ANSYS, the different physical phenomena of the wire
bonding process are considered using finite element simulation for the complex
plastic deformation of the wire and reduced order models for the transient dynamics
of the transducer, wire, substrate and bond formation. The model parameters such
as the coefficients of friction between bond tool and wire and between wire and
substrate were determined for aluminium and copper wire in experiments with a
test rig specially developed for the requirements of heavy wire bonding. To reduce
simulation time, for the finite element simulation a restart analysis and high
performance computing is utilized. Detailed analysis of the bond formation showed,
that the normal pressure distribution in the contact between wire and substrate
has high impact on bond formation and distribution of welded areas in the contact
area.
author:
- first_name: Reinhard
full_name: Schemmel, Reinhard
id: '28647'
last_name: Schemmel
- first_name: Viktor
full_name: Krieger, Viktor
last_name: Krieger
- first_name: Tobias
full_name: Hemsel, Tobias
id: '210'
last_name: Hemsel
- first_name: Walter
full_name: Sextro, Walter
id: '21220'
last_name: Sextro
citation:
ama: Schemmel R, Krieger V, Hemsel T, Sextro W. Co-simulation of MATLAB and ANSYS
for ultrasonic wire bonding process optimization. Microelectronics Reliability.
2021;119:114077. doi:https://doi.org/10.1016/j.microrel.2021.114077
apa: Schemmel, R., Krieger, V., Hemsel, T., & Sextro, W. (2021). Co-simulation
of MATLAB and ANSYS for ultrasonic wire bonding process optimization. Microelectronics
Reliability, 119, 114077. https://doi.org/10.1016/j.microrel.2021.114077
bibtex: '@article{Schemmel_Krieger_Hemsel_Sextro_2021, title={Co-simulation of MATLAB
and ANSYS for ultrasonic wire bonding process optimization}, volume={119}, DOI={https://doi.org/10.1016/j.microrel.2021.114077},
journal={Microelectronics Reliability}, author={Schemmel, Reinhard and Krieger,
Viktor and Hemsel, Tobias and Sextro, Walter}, year={2021}, pages={114077} }'
chicago: 'Schemmel, Reinhard, Viktor Krieger, Tobias Hemsel, and Walter Sextro.
“Co-Simulation of MATLAB and ANSYS for Ultrasonic Wire Bonding Process Optimization.”
Microelectronics Reliability 119 (2021): 114077. https://doi.org/10.1016/j.microrel.2021.114077.'
ieee: 'R. Schemmel, V. Krieger, T. Hemsel, and W. Sextro, “Co-simulation of MATLAB
and ANSYS for ultrasonic wire bonding process optimization,” Microelectronics
Reliability, vol. 119, p. 114077, 2021, doi: https://doi.org/10.1016/j.microrel.2021.114077.'
mla: Schemmel, Reinhard, et al. “Co-Simulation of MATLAB and ANSYS for Ultrasonic
Wire Bonding Process Optimization.” Microelectronics Reliability, vol.
119, 2021, p. 114077, doi:https://doi.org/10.1016/j.microrel.2021.114077.
short: R. Schemmel, V. Krieger, T. Hemsel, W. Sextro, Microelectronics Reliability
119 (2021) 114077.
date_created: 2021-03-10T09:37:02Z
date_updated: 2023-09-21T14:15:33Z
department:
- _id: '151'
doi: https://doi.org/10.1016/j.microrel.2021.114077
intvolume: ' 119'
keyword:
- Ultrasonic heavy wire bonding
- Co-simulation
- ANSYS
- MATLAB
- Process optimization
- Friction coefficient
- Copper-copper
- Aluminium-copper
language:
- iso: eng
page: '114077'
publication: Microelectronics Reliability
publication_identifier:
issn:
- 0026-2714
publication_status: published
quality_controlled: '1'
status: public
title: Co-simulation of MATLAB and ANSYS for ultrasonic wire bonding process optimization
type: journal_article
user_id: '210'
volume: 119
year: '2021'
...
---
_id: '46318'
abstract:
- lang: eng
text: 'Multi-objective (MO) optimization, i.e., the simultaneous optimization of
multiple conflicting objectives, is gaining more and more attention in various
research areas, such as evolutionary computation, machine learning (e.g., (hyper-)parameter
optimization), or logistics (e.g., vehicle routing). Many works in this domain
mention the structural problem property of multimodality as a challenge from two
classical perspectives: (1) finding all globally optimal solution sets, and (2)
avoiding to get trapped in local optima. Interestingly, these streams seem to
transfer many traditional concepts of single-objective (SO) optimization into
claims, assumptions, or even terminology regarding the MO domain, but mostly neglect
the understanding of the structural properties as well as the algorithmic search
behavior on a problem’s landscape. However, some recent works counteract this
trend, by investigating the fundamentals and characteristics of MO problems using
new visualization techniques and gaining surprising insights. Using these visual
insights, this work proposes a step towards a unified terminology to capture multimodality
and locality in a broader way than it is usually done. This enables us to investigate
current research activities in multimodal continuous MO optimization and to highlight
new implications and promising research directions for the design of benchmark
suites, the discovery of MO landscape features, the development of new MO (or
even SO) optimization algorithms, and performance indicators. For all these topics,
we provide a review of ideas and methods but also an outlook on future challenges,
research potential and perspectives that result from recent developments.'
author:
- first_name: Christian
full_name: Grimme, Christian
last_name: Grimme
- first_name: Pascal
full_name: Kerschke, Pascal
last_name: Kerschke
- first_name: Pelin
full_name: Aspar, Pelin
last_name: Aspar
- first_name: Heike
full_name: Trautmann, Heike
id: '100740'
last_name: Trautmann
orcid: 0000-0002-9788-8282
- first_name: Mike
full_name: Preuss, Mike
last_name: Preuss
- first_name: André H.
full_name: Deutz, André H.
last_name: Deutz
- first_name: Hao
full_name: Wang, Hao
last_name: Wang
- first_name: Michael
full_name: Emmerich, Michael
last_name: Emmerich
citation:
ama: 'Grimme C, Kerschke P, Aspar P, et al. Peeking beyond peaks: Challenges and
research potentials of continuous multimodal multi-objective optimization. Computers
& Operations Research. 2021;136:105489. doi:https://doi.org/10.1016/j.cor.2021.105489'
apa: 'Grimme, C., Kerschke, P., Aspar, P., Trautmann, H., Preuss, M., Deutz, A.
H., Wang, H., & Emmerich, M. (2021). Peeking beyond peaks: Challenges and
research potentials of continuous multimodal multi-objective optimization. Computers
& Operations Research, 136, 105489. https://doi.org/10.1016/j.cor.2021.105489'
bibtex: '@article{Grimme_Kerschke_Aspar_Trautmann_Preuss_Deutz_Wang_Emmerich_2021,
title={Peeking beyond peaks: Challenges and research potentials of continuous
multimodal multi-objective optimization}, volume={136}, DOI={https://doi.org/10.1016/j.cor.2021.105489},
journal={Computers & Operations Research}, author={Grimme, Christian and Kerschke,
Pascal and Aspar, Pelin and Trautmann, Heike and Preuss, Mike and Deutz, André
H. and Wang, Hao and Emmerich, Michael}, year={2021}, pages={105489} }'
chicago: 'Grimme, Christian, Pascal Kerschke, Pelin Aspar, Heike Trautmann, Mike
Preuss, André H. Deutz, Hao Wang, and Michael Emmerich. “Peeking beyond Peaks:
Challenges and Research Potentials of Continuous Multimodal Multi-Objective Optimization.”
Computers & Operations Research 136 (2021): 105489. https://doi.org/10.1016/j.cor.2021.105489.'
ieee: 'C. Grimme et al., “Peeking beyond peaks: Challenges and research potentials
of continuous multimodal multi-objective optimization,” Computers & Operations
Research, vol. 136, p. 105489, 2021, doi: https://doi.org/10.1016/j.cor.2021.105489.'
mla: 'Grimme, Christian, et al. “Peeking beyond Peaks: Challenges and Research Potentials
of Continuous Multimodal Multi-Objective Optimization.” Computers & Operations
Research, vol. 136, 2021, p. 105489, doi:https://doi.org/10.1016/j.cor.2021.105489.'
short: C. Grimme, P. Kerschke, P. Aspar, H. Trautmann, M. Preuss, A.H. Deutz, H.
Wang, M. Emmerich, Computers & Operations Research 136 (2021) 105489.
date_created: 2023-08-04T07:28:34Z
date_updated: 2023-10-16T12:58:42Z
department:
- _id: '34'
- _id: '819'
doi: https://doi.org/10.1016/j.cor.2021.105489
intvolume: ' 136'
keyword:
- Multimodal optimization
- Multi-objective continuous optimization
- Landscape analysis
- Visualization
- Benchmarking
- Theory
- Algorithms
language:
- iso: eng
page: '105489'
publication: Computers & Operations Research
publication_identifier:
issn:
- 0305-0548
status: public
title: 'Peeking beyond peaks: Challenges and research potentials of continuous multimodal
multi-objective optimization'
type: journal_article
user_id: '15504'
volume: 136
year: '2021'
...
---
_id: '48853'
abstract:
- lang: eng
text: In practise, it is often desirable to provide the decision-maker with a rich
set of diverse solutions of decent quality instead of just a single solution.
In this paper we study evolutionary diversity optimization for the knapsack problem
(KP). Our goal is to evolve a population of solutions that all have a profit of
at least (1 - {$ϵ$}) {$\cdot$} OPT, where OPT is the value of an optimal solution.
Furthermore, they should differ in structure with respect to an entropy-based
diversity measure. To this end we propose a simple ({$\mu$} + 1)-EA with initial
approximate solutions calculated by a well-known FPTAS for the KP. We investigate
the effect of different standard mutation operators and introduce biased mutation
and crossover which puts strong probability on flipping bits of low and/or high
frequency within the population. An experimental study on different instances
and settings shows that the proposed mutation operators in most cases perform
slightly inferior in the long term, but show strong benefits if the number of
function evaluations is severely limited.
author:
- first_name: Jakob
full_name: Bossek, Jakob
id: '102979'
last_name: Bossek
orcid: 0000-0002-4121-4668
- first_name: Aneta
full_name: Neumann, Aneta
last_name: Neumann
- first_name: Frank
full_name: Neumann, Frank
last_name: Neumann
citation:
ama: 'Bossek J, Neumann A, Neumann F. Breeding Diverse Packings for the Knapsack
Problem by Means of Diversity-Tailored Evolutionary Algorithms. In: Proceedings
of the Genetic and Evolutionary Computation Conference. GECCO ’21. Association
for Computing Machinery; 2021:556–564. doi:10.1145/3449639.3459364'
apa: Bossek, J., Neumann, A., & Neumann, F. (2021). Breeding Diverse Packings
for the Knapsack Problem by Means of Diversity-Tailored Evolutionary Algorithms.
Proceedings of the Genetic and Evolutionary Computation Conference, 556–564.
https://doi.org/10.1145/3449639.3459364
bibtex: '@inproceedings{Bossek_Neumann_Neumann_2021, place={New York, NY, USA},
series={GECCO ’21}, title={Breeding Diverse Packings for the Knapsack Problem
by Means of Diversity-Tailored Evolutionary Algorithms}, DOI={10.1145/3449639.3459364},
booktitle={Proceedings of the Genetic and Evolutionary Computation Conference},
publisher={Association for Computing Machinery}, author={Bossek, Jakob and Neumann,
Aneta and Neumann, Frank}, year={2021}, pages={556–564}, collection={GECCO ’21}
}'
chicago: 'Bossek, Jakob, Aneta Neumann, and Frank Neumann. “Breeding Diverse Packings
for the Knapsack Problem by Means of Diversity-Tailored Evolutionary Algorithms.”
In Proceedings of the Genetic and Evolutionary Computation Conference,
556–564. GECCO ’21. New York, NY, USA: Association for Computing Machinery, 2021.
https://doi.org/10.1145/3449639.3459364.'
ieee: 'J. Bossek, A. Neumann, and F. Neumann, “Breeding Diverse Packings for the
Knapsack Problem by Means of Diversity-Tailored Evolutionary Algorithms,” in Proceedings
of the Genetic and Evolutionary Computation Conference, 2021, pp. 556–564,
doi: 10.1145/3449639.3459364.'
mla: Bossek, Jakob, et al. “Breeding Diverse Packings for the Knapsack Problem by
Means of Diversity-Tailored Evolutionary Algorithms.” Proceedings of the Genetic
and Evolutionary Computation Conference, Association for Computing Machinery,
2021, pp. 556–564, doi:10.1145/3449639.3459364.
short: 'J. Bossek, A. Neumann, F. Neumann, in: Proceedings of the Genetic and Evolutionary
Computation Conference, Association for Computing Machinery, New York, NY, USA,
2021, pp. 556–564.'
date_created: 2023-11-14T15:58:54Z
date_updated: 2023-12-13T10:45:22Z
department:
- _id: '819'
doi: 10.1145/3449639.3459364
extern: '1'
keyword:
- evolutionary algorithms
- evolutionary diversity optimization
- knapsack problem
- tailored operators
language:
- iso: eng
page: 556–564
place: New York, NY, USA
publication: Proceedings of the Genetic and Evolutionary Computation Conference
publication_identifier:
isbn:
- 978-1-4503-8350-9
publication_status: published
publisher: Association for Computing Machinery
series_title: GECCO ’21
status: public
title: Breeding Diverse Packings for the Knapsack Problem by Means of Diversity-Tailored
Evolutionary Algorithms
type: conference
user_id: '102979'
year: '2021'
...
---
_id: '48860'
abstract:
- lang: eng
text: In the area of evolutionary computation the calculation of diverse sets of
high-quality solutions to a given optimization problem has gained momentum in
recent years under the term evolutionary diversity optimization. Theoretical insights
into the working principles of baseline evolutionary algorithms for diversity
optimization are still rare. In this paper we study the well-known Minimum Spanning
Tree problem (MST) in the context of diversity optimization where population diversity
is measured by the sum of pairwise edge overlaps. Theoretical results provide
insights into the fitness landscape of the MST diversity optimization problem
pointing out that even for a population of {$\mu$} = 2 fitness plateaus (of constant
length) can be reached, but nevertheless diverse sets can be calculated in polynomial
time. We supplement our theoretical results with a series of experiments for the
unconstrained and constraint case where all solutions need to fulfill a minimal
quality threshold. Our results show that a simple ({$\mu$} + 1)-EA can effectively
compute a diversified population of spanning trees of high quality.
author:
- first_name: Jakob
full_name: Bossek, Jakob
id: '102979'
last_name: Bossek
orcid: 0000-0002-4121-4668
- first_name: Frank
full_name: Neumann, Frank
last_name: Neumann
citation:
ama: 'Bossek J, Neumann F. Evolutionary Diversity Optimization and the Minimum Spanning
Tree Problem. In: Proceedings of the Genetic and Evolutionary Computation Conference.
GECCO ’21. Association for Computing Machinery; 2021:198–206. doi:10.1145/3449639.3459363'
apa: Bossek, J., & Neumann, F. (2021). Evolutionary Diversity Optimization and
the Minimum Spanning Tree Problem. Proceedings of the Genetic and Evolutionary
Computation Conference, 198–206. https://doi.org/10.1145/3449639.3459363
bibtex: '@inproceedings{Bossek_Neumann_2021, place={New York, NY, USA}, series={GECCO
’21}, title={Evolutionary Diversity Optimization and the Minimum Spanning Tree
Problem}, DOI={10.1145/3449639.3459363},
booktitle={Proceedings of the Genetic and Evolutionary Computation Conference},
publisher={Association for Computing Machinery}, author={Bossek, Jakob and Neumann,
Frank}, year={2021}, pages={198–206}, collection={GECCO ’21} }'
chicago: 'Bossek, Jakob, and Frank Neumann. “Evolutionary Diversity Optimization
and the Minimum Spanning Tree Problem.” In Proceedings of the Genetic and Evolutionary
Computation Conference, 198–206. GECCO ’21. New York, NY, USA: Association
for Computing Machinery, 2021. https://doi.org/10.1145/3449639.3459363.'
ieee: 'J. Bossek and F. Neumann, “Evolutionary Diversity Optimization and the Minimum
Spanning Tree Problem,” in Proceedings of the Genetic and Evolutionary Computation
Conference, 2021, pp. 198–206, doi: 10.1145/3449639.3459363.'
mla: Bossek, Jakob, and Frank Neumann. “Evolutionary Diversity Optimization and
the Minimum Spanning Tree Problem.” Proceedings of the Genetic and Evolutionary
Computation Conference, Association for Computing Machinery, 2021, pp. 198–206,
doi:10.1145/3449639.3459363.
short: 'J. Bossek, F. Neumann, in: Proceedings of the Genetic and Evolutionary Computation
Conference, Association for Computing Machinery, New York, NY, USA, 2021, pp.
198–206.'
date_created: 2023-11-14T15:58:55Z
date_updated: 2023-12-13T10:45:37Z
department:
- _id: '819'
doi: 10.1145/3449639.3459363
extern: '1'
keyword:
- evolutionary algorithms
- evolutionary diversity optimization
- minimum spanning tree
- runtime analysis
language:
- iso: eng
page: 198–206
place: New York, NY, USA
publication: Proceedings of the Genetic and Evolutionary Computation Conference
publication_identifier:
isbn:
- 978-1-4503-8350-9
publication_status: published
publisher: Association for Computing Machinery
series_title: GECCO ’21
status: public
title: Evolutionary Diversity Optimization and the Minimum Spanning Tree Problem
type: conference
user_id: '102979'
year: '2021'
...
---
_id: '48854'
abstract:
- lang: eng
text: We contribute to the theoretical understanding of randomized search heuristics
for dynamic problems. We consider the classical vertex coloring problem on graphs
and investigate the dynamic setting where edges are added to the current graph.
We then analyze the expected time for randomized search heuristics to recompute
high quality solutions. The (1+1) Evolutionary Algorithm and RLS operate in a
setting where the number of colors is bounded and we are minimizing the number
of conflicts. Iterated local search algorithms use an unbounded color palette
and aim to use the smallest colors and, consequently, the smallest number of colors.
We identify classes of bipartite graphs where reoptimization is as hard as or
even harder than optimization from scratch, i.e., starting with a random initialization.
Even adding a single edge can lead to hard symmetry problems. However, graph classes
that are hard for one algorithm turn out to be easy for others. In most cases
our bounds show that reoptimization is faster than optimizing from scratch. We
further show that tailoring mutation operators to parts of the graph where changes
have occurred can significantly reduce the expected reoptimization time. In most
settings the expected reoptimization time for such tailored algorithms is linear
in the number of added edges. However, tailored algorithms cannot prevent exponential
times in settings where the original algorithm is inefficient.
author:
- first_name: Jakob
full_name: Bossek, Jakob
id: '102979'
last_name: Bossek
orcid: 0000-0002-4121-4668
- first_name: Frank
full_name: Neumann, Frank
last_name: Neumann
- first_name: Pan
full_name: Peng, Pan
last_name: Peng
- first_name: Dirk
full_name: Sudholt, Dirk
last_name: Sudholt
citation:
ama: Bossek J, Neumann F, Peng P, Sudholt D. Time Complexity Analysis of Randomized
Search Heuristics for the Dynamic Graph Coloring Problem. Algorithmica.
2021;83(10):3148–3179. doi:10.1007/s00453-021-00838-3
apa: Bossek, J., Neumann, F., Peng, P., & Sudholt, D. (2021). Time Complexity
Analysis of Randomized Search Heuristics for the Dynamic Graph Coloring Problem.
Algorithmica, 83(10), 3148–3179. https://doi.org/10.1007/s00453-021-00838-3
bibtex: '@article{Bossek_Neumann_Peng_Sudholt_2021, title={Time Complexity Analysis
of Randomized Search Heuristics for the Dynamic Graph Coloring Problem}, volume={83},
DOI={10.1007/s00453-021-00838-3},
number={10}, journal={Algorithmica}, author={Bossek, Jakob and Neumann, Frank
and Peng, Pan and Sudholt, Dirk}, year={2021}, pages={3148–3179} }'
chicago: 'Bossek, Jakob, Frank Neumann, Pan Peng, and Dirk Sudholt. “Time Complexity
Analysis of Randomized Search Heuristics for the Dynamic Graph Coloring Problem.”
Algorithmica 83, no. 10 (2021): 3148–3179. https://doi.org/10.1007/s00453-021-00838-3.'
ieee: 'J. Bossek, F. Neumann, P. Peng, and D. Sudholt, “Time Complexity Analysis
of Randomized Search Heuristics for the Dynamic Graph Coloring Problem,” Algorithmica,
vol. 83, no. 10, pp. 3148–3179, 2021, doi: 10.1007/s00453-021-00838-3.'
mla: Bossek, Jakob, et al. “Time Complexity Analysis of Randomized Search Heuristics
for the Dynamic Graph Coloring Problem.” Algorithmica, vol. 83, no. 10,
2021, pp. 3148–3179, doi:10.1007/s00453-021-00838-3.
short: J. Bossek, F. Neumann, P. Peng, D. Sudholt, Algorithmica 83 (2021) 3148–3179.
date_created: 2023-11-14T15:58:54Z
date_updated: 2023-12-13T10:51:34Z
department:
- _id: '819'
doi: 10.1007/s00453-021-00838-3
intvolume: ' 83'
issue: '10'
keyword:
- Dynamic optimization
- Evolutionary algorithms
- Running time analysis
language:
- iso: eng
page: 3148–3179
publication: Algorithmica
publication_identifier:
issn:
- 0178-4617
status: public
title: Time Complexity Analysis of Randomized Search Heuristics for the Dynamic Graph
Coloring Problem
type: journal_article
user_id: '102979'
volume: 83
year: '2021'
...
---
_id: '19609'
abstract:
- lang: eng
text: "Modern services comprise interconnected components,\r\ne.g., microservices
in a service mesh, that can scale and\r\nrun on multiple nodes across the network
on demand. To process\r\nincoming traffic, service components have to be instantiated
and\r\ntraffic assigned to these instances, taking capacities and changing\r\ndemands
into account. This challenge is usually solved with\r\ncustom approaches designed
by experts. While this typically\r\nworks well for the considered scenario, the
models often rely\r\non unrealistic assumptions or on knowledge that is not available\r\nin
practice (e.g., a priori knowledge).\r\n\r\nWe propose a novel deep reinforcement
learning approach that\r\nlearns how to best coordinate services and is geared
towards\r\nrealistic assumptions. It interacts with the network and relies on\r\navailable,
possibly delayed monitoring information. Rather than\r\ndefining a complex model
or an algorithm how to achieve an\r\nobjective, our model-free approach adapts
to various objectives\r\nand traffic patterns. An agent is trained offline without
expert\r\nknowledge and then applied online with minimal overhead. Compared\r\nto
a state-of-the-art heuristic, it significantly improves flow\r\nthroughput and
overall network utility on real-world network\r\ntopologies and traffic traces.
It also learns to optimize different\r\nobjectives, generalizes to scenarios with
unseen, stochastic traffic\r\npatterns, and scales to large real-world networks."
author:
- first_name: Stefan Balthasar
full_name: Schneider, Stefan Balthasar
id: '35343'
last_name: Schneider
orcid: 0000-0001-8210-4011
- first_name: Adnan
full_name: Manzoor, Adnan
last_name: Manzoor
- first_name: Haydar
full_name: Qarawlus, Haydar
last_name: Qarawlus
- first_name: Rafael
full_name: Schellenberg, Rafael
last_name: Schellenberg
- first_name: Holger
full_name: Karl, Holger
id: '126'
last_name: Karl
- first_name: Ramin
full_name: Khalili, Ramin
last_name: Khalili
- first_name: Artur
full_name: Hecker, Artur
last_name: Hecker
citation:
ama: 'Schneider SB, Manzoor A, Qarawlus H, et al. Self-Driving Network and Service
Coordination Using Deep Reinforcement Learning. In: IEEE International Conference
on Network and Service Management (CNSM). IEEE; 2020.'
apa: Schneider, S. B., Manzoor, A., Qarawlus, H., Schellenberg, R., Karl, H., Khalili,
R., & Hecker, A. (2020). Self-Driving Network and Service Coordination Using
Deep Reinforcement Learning. In IEEE International Conference on Network and
Service Management (CNSM). IEEE.
bibtex: '@inproceedings{Schneider_Manzoor_Qarawlus_Schellenberg_Karl_Khalili_Hecker_2020,
title={Self-Driving Network and Service Coordination Using Deep Reinforcement
Learning}, booktitle={IEEE International Conference on Network and Service Management
(CNSM)}, publisher={IEEE}, author={Schneider, Stefan Balthasar and Manzoor, Adnan
and Qarawlus, Haydar and Schellenberg, Rafael and Karl, Holger and Khalili, Ramin
and Hecker, Artur}, year={2020} }'
chicago: Schneider, Stefan Balthasar, Adnan Manzoor, Haydar Qarawlus, Rafael Schellenberg,
Holger Karl, Ramin Khalili, and Artur Hecker. “Self-Driving Network and Service
Coordination Using Deep Reinforcement Learning.” In IEEE International Conference
on Network and Service Management (CNSM). IEEE, 2020.
ieee: S. B. Schneider et al., “Self-Driving Network and Service Coordination
Using Deep Reinforcement Learning,” in IEEE International Conference on Network
and Service Management (CNSM), 2020.
mla: Schneider, Stefan Balthasar, et al. “Self-Driving Network and Service Coordination
Using Deep Reinforcement Learning.” IEEE International Conference on Network
and Service Management (CNSM), IEEE, 2020.
short: 'S.B. Schneider, A. Manzoor, H. Qarawlus, R. Schellenberg, H. Karl, R. Khalili,
A. Hecker, in: IEEE International Conference on Network and Service Management
(CNSM), IEEE, 2020.'
date_created: 2020-09-22T06:28:22Z
date_updated: 2022-01-06T06:54:08Z
ddc:
- '006'
department:
- _id: '75'
file:
- access_level: open_access
content_type: application/pdf
creator: stschn
date_created: 2020-09-22T06:29:16Z
date_updated: 2020-09-22T06:36:00Z
file_id: '19610'
file_name: ris_with_copyright.pdf
file_size: 642999
relation: main_file
file_date_updated: 2020-09-22T06:36:00Z
has_accepted_license: '1'
keyword:
- self-driving networks
- self-learning
- network coordination
- service coordination
- reinforcement learning
- deep learning
- nfv
language:
- iso: eng
oa: '1'
project:
- _id: '1'
name: SFB 901
- _id: '4'
name: SFB 901 - Project Area C
- _id: '16'
name: SFB 901 - Subproject C4
publication: IEEE International Conference on Network and Service Management (CNSM)
publisher: IEEE
status: public
title: Self-Driving Network and Service Coordination Using Deep Reinforcement Learning
type: conference
user_id: '35343'
year: '2020'
...
---
_id: '19976'
abstract:
- lang: eng
text: The aim to reduce pollutant emission has led to a trend towards lightweight
construction in car body development during the last years. As a consequence of
the resulting need for multi-material design, mechanical joining technologies
become increasingly important. Mechanical joining allows for the combination of
dissimilar materials, while thermic joining techniques reach their limits. Self-piercing
riveting enables the joining of dissimilar materials by using semi-tubular rivets
as mechanical fasteners. The rivet production, however, is costly and time-consuming,
as the rivets generally have to be hardened, tempered and coated after forming,
in order to achieve an adequate strength and corrosion resistance. A promising
approach to improve the efficiency of the rivet manufacturing is the use of high-strength
high nitrogen steel as rivet material because these additional process steps would
not be necessary anymore. As a result of the comparatively high nitrogen content,
such steels have various beneficial properties like higher strength, good ductility
and improved corrosion resistance. By cold bulk forming of high nitrogen steels
high-strength parts can be manufactured due to the strengthening which is caused
by the high strain hardening. However, high tool loads thereby have to be expected
and are a major challenge during the production process. Consequently, there is
a need for appropriate forming strategies. This paper presents key aspects concerning
the process design for the manufacturing of semi-tubular self-piercing rivets
made of high-strength steel. The aim is to produce the rivets in several forming
stages without intermediate heat treatment between the single stages. Due to the
high strain hardening of the material, a two stage forming concept will be investigated.
Cup-backward extrusion is chosen as the first process step in order to form the
rivet shank without forming the rivet foot. Thus, the strain hardening effects
in the area of the rivet foot are minimized and the tool loads during the following
process step can be reduced. During the second and final forming stage the detailed
geometry of the rivet foot and the rivet head is formed. In this context, the
effect of different variations, for example concerning the final geometry of the
rivet foot, on the tool load is investigated using multistage numerical analysis.
Furthermore, the influence of the process temperature on occurring stresses is
analysed. Based on the results of the investigations, an adequate forming strategy
and a tool concept for the manufacturing of semi-tubular self-piercing rivets
made of high-strength steel are presented.
citation:
ama: Kuball C-M, Uhe B, Meschut G, Merklein M, eds. Process Design for the Forming
of Semi-Tubular Self-Piercing Rivets Made of High Nitrogen Steel. Vol 50.;
2020:280-285. doi:10.1016/j.promfg.2020.08.052
apa: Kuball, C.-M., Uhe, B., Meschut, G., & Merklein, M. (Eds.). (2020). Process
design for the forming of semi-tubular self-piercing rivets made of high nitrogen
steel (Vol. 50, pp. 280–285). https://doi.org/10.1016/j.promfg.2020.08.052
bibtex: '@book{Kuball_Uhe_Meschut_Merklein_2020, series={Procedia Manufacturing},
title={Process design for the forming of semi-tubular self-piercing rivets made
of high nitrogen steel}, volume={50}, DOI={10.1016/j.promfg.2020.08.052},
year={2020}, pages={280–285}, collection={Procedia Manufacturing} }'
chicago: Kuball, Clara-Maria, Benedikt Uhe, Gerson Meschut, and Marion Merklein,
eds. Process Design for the Forming of Semi-Tubular Self-Piercing Rivets Made
of High Nitrogen Steel. Vol. 50. Procedia Manufacturing, 2020. https://doi.org/10.1016/j.promfg.2020.08.052.
ieee: C.-M. Kuball, B. Uhe, G. Meschut, and M. Merklein, Eds., Process design
for the forming of semi-tubular self-piercing rivets made of high nitrogen steel,
vol. 50. 2020, pp. 280–285.
mla: Kuball, Clara-Maria, et al., editors. Process Design for the Forming of
Semi-Tubular Self-Piercing Rivets Made of High Nitrogen Steel. Vol. 50, 2020,
pp. 280–85, doi:10.1016/j.promfg.2020.08.052.
short: C.-M. Kuball, B. Uhe, G. Meschut, M. Merklein, eds., Process Design for the
Forming of Semi-Tubular Self-Piercing Rivets Made of High Nitrogen Steel, 2020.
date_created: 2020-10-12T08:30:08Z
date_updated: 2022-01-06T06:54:17Z
department:
- _id: '157'
doi: 10.1016/j.promfg.2020.08.052
editor:
- first_name: Clara-Maria
full_name: Kuball, Clara-Maria
last_name: Kuball
- first_name: Benedikt
full_name: Uhe, Benedikt
id: '38131'
last_name: Uhe
- first_name: Gerson
full_name: Meschut, Gerson
id: '32056'
last_name: Meschut
orcid: 0000-0002-2763-1246
- first_name: Marion
full_name: Merklein, Marion
last_name: Merklein
intvolume: ' 50'
keyword:
- high nitrogen steel
- self-piercing riveting
- joining by forming
- bulk forming
- tool design
language:
- iso: eng
page: 280-285
publication_status: published
quality_controlled: '1'
series_title: Procedia Manufacturing
status: public
title: Process design for the forming of semi-tubular self-piercing rivets made of
high nitrogen steel
type: conference_editor
user_id: '38131'
volume: 50
year: '2020'
...
---
_id: '17370'
abstract:
- lang: eng
text: " We consider a natural extension to the metric uncapacitated Facility Location
Problem (FLP) in which requests ask for different commodities out of a finite
set \\( S \\) of commodities.\r\n Ravi and Sinha (SODA 2004) introduced the model
as the \\emph{Multi-Commodity Facility Location Problem} (MFLP) and considered
it an offline optimization problem.\r\n The model itself is similar to the FLP:
i.e., requests are located at points of a finite metric space and the task of
an algorithm is to construct facilities and assign requests to facilities while
minimizing the construction cost and the sum over all assignment distances.\r\n
\ In addition, requests and facilities are heterogeneous; they request or offer
multiple commodities out of $S$.\r\n A request has to be connected to a set of
facilities jointly offering the commodities demanded by it.\r\n In comparison
to the FLP, an algorithm has to decide not only if and where to place facilities,
but also which commodities to offer at each.\r\n\r\n To the best of our knowledge
we are the first to study the problem in its online variant in which requests,
their positions and their commodities are not known beforehand but revealed over
time.\r\n We present results regarding the competitive ratio.\r\n On the one
hand, we show that heterogeneity influences the competitive ratio by developing
a lower bound on the competitive ratio for any randomized online algorithm of
\\( \\Omega ( \\sqrt{|S|} + \\frac{\\log n}{\\log \\log n} ) \\) that already
holds for simple line metrics.\r\n Here, \\( n \\) is the number of requests.\r\n
\ On the other side, we establish a deterministic \\( \\mathcal{O}(\\sqrt{|S|}
\\cdot \\log n) \\)-competitive algorithm and a randomized \\( \\mathcal{O}(\\sqrt{|S|}
\\cdot \\frac{\\log n}{\\log \\log n} ) \\)-competitive algorithm.\r\n Further,
we show that when considering a more special class of cost functions for the construction
cost of a facility, the competitive ratio decreases given by our deterministic
algorithm depending on the function."
author:
- first_name: Jannik
full_name: Castenow, Jannik
id: '38705'
last_name: Castenow
- first_name: Björn
full_name: Feldkord, Björn
id: '22704'
last_name: Feldkord
- first_name: Till
full_name: Knollmann, Till
id: '39241'
last_name: Knollmann
orcid: 0000-0003-2014-4696
- first_name: Manuel
full_name: Malatyali, Manuel
last_name: Malatyali
- first_name: Friedhelm
full_name: Meyer auf der Heide, Friedhelm
id: '15523'
last_name: Meyer auf der Heide
citation:
ama: 'Castenow J, Feldkord B, Knollmann T, Malatyali M, Meyer auf der Heide F. The
Online Multi-Commodity Facility Location Problem. In: Proceedings of the 32nd
ACM Symposium on Parallelism in Algorithms and Architectures. ; 2020. doi:10.1145/3350755.3400281'
apa: Castenow, J., Feldkord, B., Knollmann, T., Malatyali, M., & Meyer auf der
Heide, F. (2020). The Online Multi-Commodity Facility Location Problem. In Proceedings
of the 32nd ACM Symposium on Parallelism in Algorithms and Architectures.
https://doi.org/10.1145/3350755.3400281
bibtex: '@inproceedings{Castenow_Feldkord_Knollmann_Malatyali_Meyer auf der Heide_2020,
title={The Online Multi-Commodity Facility Location Problem}, DOI={10.1145/3350755.3400281},
booktitle={Proceedings of the 32nd ACM Symposium on Parallelism in Algorithms
and Architectures}, author={Castenow, Jannik and Feldkord, Björn and Knollmann,
Till and Malatyali, Manuel and Meyer auf der Heide, Friedhelm}, year={2020} }'
chicago: Castenow, Jannik, Björn Feldkord, Till Knollmann, Manuel Malatyali, and
Friedhelm Meyer auf der Heide. “The Online Multi-Commodity Facility Location Problem.”
In Proceedings of the 32nd ACM Symposium on Parallelism in Algorithms and Architectures,
2020. https://doi.org/10.1145/3350755.3400281.
ieee: J. Castenow, B. Feldkord, T. Knollmann, M. Malatyali, and F. Meyer auf der
Heide, “The Online Multi-Commodity Facility Location Problem,” in Proceedings
of the 32nd ACM Symposium on Parallelism in Algorithms and Architectures,
2020.
mla: Castenow, Jannik, et al. “The Online Multi-Commodity Facility Location Problem.”
Proceedings of the 32nd ACM Symposium on Parallelism in Algorithms and Architectures,
2020, doi:10.1145/3350755.3400281.
short: 'J. Castenow, B. Feldkord, T. Knollmann, M. Malatyali, F. Meyer auf der Heide,
in: Proceedings of the 32nd ACM Symposium on Parallelism in Algorithms and Architectures,
2020.'
date_created: 2020-07-14T07:53:20Z
date_updated: 2022-01-06T06:53:10Z
ddc:
- '000'
department:
- _id: '63'
doi: 10.1145/3350755.3400281
external_id:
arxiv:
- '2005.08391'
file:
- access_level: closed
content_type: application/pdf
creator: tillk
date_created: 2020-07-14T07:56:52Z
date_updated: 2020-07-14T07:56:52Z
file_id: '17373'
file_name: 3350755.3400281.pdf
file_size: 1271416
relation: main_file
success: 1
file_date_updated: 2020-07-14T07:56:52Z
has_accepted_license: '1'
keyword:
- Online Multi-Commodity Facility Location
- Competitive Ratio
- Online Optimization
- Facility Location Problem
language:
- iso: eng
project:
- _id: '1'
name: SFB 901
- _id: '2'
name: SFB 901 - Project Area A
- _id: '5'
name: SFB 901 - Subproject A1
publication: Proceedings of the 32nd ACM Symposium on Parallelism in Algorithms and
Architectures
publication_identifier:
isbn:
- '9781450369350'
publication_status: published
status: public
title: The Online Multi-Commodity Facility Location Problem
type: conference
user_id: '39241'
year: '2020'
...
---
_id: '20143'
author:
- first_name: Mortaza
full_name: Otroshi, Mortaza
id: '71269'
last_name: Otroshi
orcid: 0000-0002-8652-9209
- first_name: Moritz
full_name: Rossel, Moritz
last_name: Rossel
- first_name: Gerson
full_name: Meschut, Gerson
id: '32056'
last_name: Meschut
orcid: 0000-0002-2763-1246
citation:
ama: Otroshi M, Rossel M, Meschut G. Stress state dependent damage modeling of self-pierce
riveting process simulation using GISSMO damage model. Journal of Advanced
Joining Processes. 2020;1. doi:10.1016/j.jajp.2020.100015
apa: Otroshi, M., Rossel, M., & Meschut, G. (2020). Stress state dependent damage
modeling of self-pierce riveting process simulation using GISSMO damage model.
Journal of Advanced Joining Processes, 1. https://doi.org/10.1016/j.jajp.2020.100015
bibtex: '@article{Otroshi_Rossel_Meschut_2020, title={Stress state dependent damage
modeling of self-pierce riveting process simulation using GISSMO damage model},
volume={1}, DOI={10.1016/j.jajp.2020.100015},
journal={Journal of Advanced Joining Processes}, publisher={Elsevier}, author={Otroshi,
Mortaza and Rossel, Moritz and Meschut, Gerson}, year={2020} }'
chicago: Otroshi, Mortaza, Moritz Rossel, and Gerson Meschut. “Stress State Dependent
Damage Modeling of Self-Pierce Riveting Process Simulation Using GISSMO Damage
Model.” Journal of Advanced Joining Processes 1 (2020). https://doi.org/10.1016/j.jajp.2020.100015.
ieee: 'M. Otroshi, M. Rossel, and G. Meschut, “Stress state dependent damage modeling
of self-pierce riveting process simulation using GISSMO damage model,” Journal
of Advanced Joining Processes, vol. 1, 2020, doi: 10.1016/j.jajp.2020.100015.'
mla: Otroshi, Mortaza, et al. “Stress State Dependent Damage Modeling of Self-Pierce
Riveting Process Simulation Using GISSMO Damage Model.” Journal of Advanced
Joining Processes, vol. 1, Elsevier, 2020, doi:10.1016/j.jajp.2020.100015.
short: M. Otroshi, M. Rossel, G. Meschut, Journal of Advanced Joining Processes
1 (2020).
date_created: 2020-10-20T14:49:15Z
date_updated: 2022-04-25T07:49:50Z
department:
- _id: '157'
doi: 10.1016/j.jajp.2020.100015
intvolume: ' 1'
keyword:
- Self-pierce riveting
- Ductile fracture
- Damage modeling
- GISSMO damage model
language:
- iso: eng
main_file_link:
- open_access: '1'
oa: '1'
publication: Journal of Advanced Joining Processes
publisher: Elsevier
quality_controlled: '1'
status: public
title: Stress state dependent damage modeling of self-pierce riveting process simulation
using GISSMO damage model
type: journal_article
user_id: '71269'
volume: 1
year: '2020'
...
---
_id: '35298'
abstract:
- lang: ger
text: Im Artikel werden drei verschiedene Lernzugänge (kom-petenzorientiertes, ästhetisches und biographisches Lernen) vorgestellt und aus
theoretischer Perspektive deren motivierender Gehalt für selbstreguliertes Lernen
in Praxisphasen des Lehramtsstudiumsherausgearbeitet. Als theoretische Grund-lage
dient die Selbstbestimmungstheorie als zentrale motivationale Theorie zur Erklärung
selbstbestimmten Handelns.
- lang: eng
text: The article addresses how motivational learning approaches (competency-oriented, aesthetic and biographical) can contribute to the professionalization
of preservice teachers during a long-term internship. As a theoretical basis,
the self-determination theory serves as a central motivational theory for explaining
self-determined action.
alternative_title:
- Ein Blick auf kompetenzorientiertes, ästhetisches und biographisches Lernen im Lehramtsstudium
author:
- first_name: Carina
full_name: Caruso, Carina
id: '23123'
last_name: Caruso
- first_name: Christine
full_name: Adammek, Christine
last_name: Adammek
- first_name: Sabrina
full_name: Bonanati, Sabrina
last_name: Bonanati
- first_name: Sybille
full_name: Wiescholek, Sybille
last_name: Wiescholek
citation:
ama: Caruso C, Adammek C, Bonanati S, Wiescholek S. Motivierende Lernzugänge als
Ausgangspunkt der Professionalisierung angehender Lehrer_innen. Herausforderung
Lehrer*innenbildung - Zeitschrift Zur Konzeption, Gestaltung Und Diskussion.
2020;3(1):18-33. doi:10.4119/hlz-2540
apa: Caruso, C., Adammek, C., Bonanati, S., & Wiescholek, S. (2020). Motivierende
Lernzugänge als Ausgangspunkt der Professionalisierung angehender Lehrer_innen.
Herausforderung Lehrer*innenbildung - Zeitschrift Zur Konzeption, Gestaltung
Und Diskussion, 3(1), 18–33. https://doi.org/10.4119/hlz-2540
bibtex: '@article{Caruso_Adammek_Bonanati_Wiescholek_2020, title={Motivierende Lernzugänge
als Ausgangspunkt der Professionalisierung angehender Lehrer_innen}, volume={3},
DOI={10.4119/hlz-2540}, number={1},
journal={Herausforderung Lehrer*innenbildung - Zeitschrift Zur Konzeption, Gestaltung
Und Diskussion}, author={Caruso, Carina and Adammek, Christine and Bonanati, Sabrina
and Wiescholek, Sybille}, year={2020}, pages={18–33} }'
chicago: 'Caruso, Carina, Christine Adammek, Sabrina Bonanati, and Sybille Wiescholek.
“Motivierende Lernzugänge als Ausgangspunkt der Professionalisierung angehender
Lehrer_innen.” Herausforderung Lehrer*innenbildung - Zeitschrift Zur Konzeption,
Gestaltung Und Diskussion 3, no. 1 (2020): 18–33. https://doi.org/10.4119/hlz-2540.'
ieee: 'C. Caruso, C. Adammek, S. Bonanati, and S. Wiescholek, “Motivierende Lernzugänge
als Ausgangspunkt der Professionalisierung angehender Lehrer_innen,” Herausforderung
Lehrer*innenbildung - Zeitschrift Zur Konzeption, Gestaltung Und Diskussion,
vol. 3, no. 1, pp. 18–33, 2020, doi: 10.4119/hlz-2540.'
mla: Caruso, Carina, et al. “Motivierende Lernzugänge als Ausgangspunkt der Professionalisierung
angehender Lehrer_innen.” Herausforderung Lehrer*innenbildung - Zeitschrift
Zur Konzeption, Gestaltung Und Diskussion, vol. 3, no. 1, 2020, pp. 18–33,
doi:10.4119/hlz-2540.
short: C. Caruso, C. Adammek, S. Bonanati, S. Wiescholek, Herausforderung Lehrer*innenbildung
- Zeitschrift Zur Konzeption, Gestaltung Und Diskussion 3 (2020) 18–33.
date_created: 2023-01-05T13:58:28Z
date_updated: 2023-01-06T12:18:16Z
doi: 10.4119/hlz-2540
intvolume: ' 3'
issue: '1'
keyword:
- ästhetische Forschung
- Biographiearbeit
- Praxissemester
- Professionalisierung
- selbstreguliertes Lernen
- Motivation / aesthetic research
- biographical work
- long-term internship
- profes-sionalization
- self-regulated learning
- motivation
language:
- iso: other
page: 18-33
publication: Herausforderung Lehrer*innenbildung - Zeitschrift Zur Konzeption, Gestaltung
Und Diskussion
publication_identifier:
issn:
- 2625-0675
publication_status: published
status: public
title: Motivierende Lernzugänge als Ausgangspunkt der Professionalisierung angehender
Lehrer_innen
type: journal_article
user_id: '86519'
volume: 3
year: '2020'
...
---
_id: '33866'
abstract:
- lang: eng
text: Helhmoltz–Kirchhoff equations of motions of vortices of an incompressible
fluid in the plane define a dynamics with singularities and this leads to a Zermelo
navigation problem describing the ship travel in such a field where the control
is the heading angle. Considering one vortex, we define a time minimization problem
which can be analyzed with the technics of geometric optimal control combined
with numerical simulations, the geometric frame being the extension of Randers
metrics in the punctured plane, with rotational symmetry. Candidates as minimizers
are parameterized thanks to the Pontryagin Maximum Principle as extremal solutions
of a Hamiltonian vector field. We analyze the time minimal solution to transfer
the ship between two points where during the transfer the ship can be either in
a strong current region in the vicinity of the vortex or in a weak current region.
The analysis is based on a micro-local classification of the extremals using mainly
the integrability properties of the dynamics due to the rotational symmetry. The
discussion is complex and related to the existence of an isolated extremal (Reeb)
circle due to the vortex singularity. The explicit computation of cut points where
the extremal curves cease to be optimal is given and the spheres are described
in the case where at the initial point the current is weak.
article_number: S10
author:
- first_name: Bernard
full_name: Bonnard, Bernard
last_name: Bonnard
- first_name: Olivier
full_name: Cots, Olivier
last_name: Cots
- first_name: Boris Edgar
full_name: Wembe Moafo, Boris Edgar
id: '95394'
last_name: Wembe Moafo
citation:
ama: 'Bonnard B, Cots O, Wembe Moafo BE. A Zermelo navigation problem with a vortex
singularity. ESAIM: Control, Optimisation and Calculus of Variations. 2020;27.
doi:10.1051/cocv/2020058'
apa: 'Bonnard, B., Cots, O., & Wembe Moafo, B. E. (2020). A Zermelo navigation
problem with a vortex singularity. ESAIM: Control, Optimisation and Calculus
of Variations, 27, Article S10. https://doi.org/10.1051/cocv/2020058'
bibtex: '@article{Bonnard_Cots_Wembe Moafo_2020, title={A Zermelo navigation problem
with a vortex singularity}, volume={27}, DOI={10.1051/cocv/2020058},
number={S10}, journal={ESAIM: Control, Optimisation and Calculus of Variations},
publisher={EDP Sciences}, author={Bonnard, Bernard and Cots, Olivier and Wembe
Moafo, Boris Edgar}, year={2020} }'
chicago: 'Bonnard, Bernard, Olivier Cots, and Boris Edgar Wembe Moafo. “A Zermelo
Navigation Problem with a Vortex Singularity.” ESAIM: Control, Optimisation
and Calculus of Variations 27 (2020). https://doi.org/10.1051/cocv/2020058.'
ieee: 'B. Bonnard, O. Cots, and B. E. Wembe Moafo, “A Zermelo navigation problem
with a vortex singularity,” ESAIM: Control, Optimisation and Calculus of Variations,
vol. 27, Art. no. S10, 2020, doi: 10.1051/cocv/2020058.'
mla: 'Bonnard, Bernard, et al. “A Zermelo Navigation Problem with a Vortex Singularity.”
ESAIM: Control, Optimisation and Calculus of Variations, vol. 27, S10,
EDP Sciences, 2020, doi:10.1051/cocv/2020058.'
short: 'B. Bonnard, O. Cots, B.E. Wembe Moafo, ESAIM: Control, Optimisation and
Calculus of Variations 27 (2020).'
date_created: 2022-10-24T12:51:05Z
date_updated: 2023-01-16T12:09:22Z
doi: 10.1051/cocv/2020058
intvolume: ' 27'
keyword:
- Computational Mathematics
- Control and Optimization
- Control and Systems Engineering
language:
- iso: eng
publication: 'ESAIM: Control, Optimisation and Calculus of Variations'
publication_identifier:
issn:
- 1292-8119
- 1262-3377
publication_status: published
publisher: EDP Sciences
status: public
title: A Zermelo navigation problem with a vortex singularity
type: journal_article
user_id: '95394'
volume: 27
year: '2020'
...
---
_id: '19974'
abstract:
- lang: eng
text: Due to the trend towards lightweight design in car body development mechanical
joining technologies become increasingly important. These techniques allow for
the joining of dissimilar materials and thus enable multi-material design, while
thermic joining methods reach their limits. Semi-tubular self-piercing riveting
is an important mechanical joining technology. The rivet production, however,
is costly and time-consuming, as the process consists of several process steps
including the heat treatment and coating of the rivets in order to achieve an
adequate strength and corrosion resistance. The use of high nitrogen steel as
rivet material leads to the possibility of reducing process steps and hence increasing
the efficiency of the process. However, the high tool loads being expected due
to the high strain hardening of the material are a major challenge during the
rivet production. Thus, there is a need for appropriate forming strategies, such
as the manufacturing of the rivets at elevated temperatures. Prior investigations
led to the conclusion that forming already at 200 °C results in a distinct reduction
of the yield strength. To create a deeper understanding of the forming behaviour
of high nitrogen steel at elevated temperatures, compression tests were conducted
in a temperature range between room temperature and 200 °C. The determined true
stress – true strain curves are the basis for the further process and tool design
of the rivet production. Another key factor for the rivet manufacturing at elevated
temperatures is the influence of the process temperature on the tribological conditions.
For this reason, ring compression tests at room temperature and 200 °C are carried
out. The friction factors are determined on the basis of calibration curves resulting
from the numerical analysis of the ring compression process. The investigations
indicate that the friction factor at 200 °C is significantly higher compared to
room temperature. This essential fact has to be taken into account for the process
and tool design for the rivet production using high nitrogen steel.
article_number: '100023'
citation:
ama: Kuball C-M, Jung R, Uhe B, Meschut G, Merklein M, eds. Influence of the
Process Temperature on the Forming Behaviour and the Friction during Bulk Forming
of High Nitrogen Steel. Vol 1.; 2020. doi:10.1016/j.jajp.2020.100023
apa: Kuball, C.-M., Jung, R., Uhe, B., Meschut, G., & Merklein, M. (Eds.). (2020).
Influence of the process temperature on the forming behaviour and the friction
during bulk forming of high nitrogen steel (No. 100023; Vol. 1). https://doi.org/10.1016/j.jajp.2020.100023
bibtex: '@book{Kuball_Jung_Uhe_Meschut_Merklein_2020, series={Journal of Advanced
Joining Processes}, title={Influence of the process temperature on the forming
behaviour and the friction during bulk forming of high nitrogen steel}, volume={1},
DOI={10.1016/j.jajp.2020.100023},
number={100023}, year={2020}, collection={Journal of Advanced Joining Processes}
}'
chicago: Kuball, Clara-Maria, R Jung, Benedikt Uhe, Gerson Meschut, and Marion Merklein,
eds. Influence of the Process Temperature on the Forming Behaviour and the
Friction during Bulk Forming of High Nitrogen Steel. Vol. 1. Journal of Advanced
Joining Processes, 2020. https://doi.org/10.1016/j.jajp.2020.100023.
ieee: C.-M. Kuball, R. Jung, B. Uhe, G. Meschut, and M. Merklein, Eds., Influence
of the process temperature on the forming behaviour and the friction during bulk
forming of high nitrogen steel, vol. 1. 2020.
mla: Kuball, Clara-Maria, et al., editors. Influence of the Process Temperature
on the Forming Behaviour and the Friction during Bulk Forming of High Nitrogen
Steel. 100023, 2020, doi:10.1016/j.jajp.2020.100023.
short: C.-M. Kuball, R. Jung, B. Uhe, G. Meschut, M. Merklein, eds., Influence of
the Process Temperature on the Forming Behaviour and the Friction during Bulk
Forming of High Nitrogen Steel, 2020.
date_created: 2020-10-12T08:23:27Z
date_updated: 2023-04-28T09:19:41Z
department:
- _id: '157'
doi: 10.1016/j.jajp.2020.100023
editor:
- first_name: Clara-Maria
full_name: Kuball, Clara-Maria
last_name: Kuball
- first_name: R
full_name: Jung, R
last_name: Jung
- first_name: Benedikt
full_name: Uhe, Benedikt
id: '38131'
last_name: Uhe
- first_name: Gerson
full_name: Meschut, Gerson
id: '32056'
last_name: Meschut
orcid: 0000-0002-2763-1246
- first_name: Marion
full_name: Merklein, Marion
last_name: Merklein
intvolume: ' 1'
keyword:
- High nitrogen steel
- Self-piercing riveting
- Joining by forming
- Bulk forming
- Strain hardening
language:
- iso: eng
publication_status: published
quality_controlled: '1'
series_title: Journal of Advanced Joining Processes
status: public
title: Influence of the process temperature on the forming behaviour and the friction
during bulk forming of high nitrogen steel
type: conference_editor
user_id: '38131'
volume: 1
year: '2020'
...