TY - JOUR
AB - Academics may actively respond to the expectations of the academic status market, which have largely been shaped by the World University Rankings (WURs). This study empirically examines how academics’ citation patterns have changed in response to the rise of an “evaluation environment” in academia. We regard the WURs to be a macro-level trigger for cementing a bibliometric-based evaluation environment in academia. Our analyses of citation patterns in papers published in two higher education journals explicitly considered three distinct periods: the pre-WURs (1990–2003), the period of WURs implementation (2004–2010), and the period of adaption to WURs (2011–2017). We applied the nonparametric Kaplan–Meier method to compare first-citation speeds of papers published across the three periods. We found that not only has first-citation speed become faster, but first-citation probability has also increased following the emergence of the WURs. Applying Cox proportional hazard models to first-citation probabilities, we identified journal impact factors and third-party funding as factors influencing first-citation probability, while other author- and paper-related factors showed limited effects. We also found that the general effects of different factors on first-citation speeds have changed with the emergence of the WURs. The findings expand our understanding of the citation patterns of academics in the rise of WURs and provide practical grounds for research policy as well as higher education policy.
AU - Lee, Soo Jeung
AU - Schneijderberg, Christian
AU - Kim, Yangson
AU - Steinhardt, Isabel
ID - 33372
IS - 17
JF - Sustainability
KW - world university rankings
KW - citation
KW - first-citation speed
KW - Minerva
KW - Studies in Higher Education
SN - 2071-1050
TI - Have Academics’ Citation Patterns Changed in Response to the Rise of World University Rankings? A Test Using First-Citation Speeds
VL - 13
ER -
TY - CONF
AU - Zahera, Hamada Mohamed Abdelsamee
AU - Heindorf, Stefan
AU - Ngonga Ngomo, Axel-Cyrille
ID - 29291
T2 - Proceedings of the 11th on Knowledge Capture Conference
TI - ASSET: A Semi-supervised Approach for Entity Typing in Knowledge Graphs
ER -
TY - CHAP
AU - Feldhans, Robert
AU - Wilke, Adrian
AU - Heindorf, Stefan
AU - Shaker, Mohammad Hossein
AU - Hammer, Barbara
AU - Ngonga Ngomo, Axel-Cyrille
AU - Hüllermeier, Eyke
ID - 29292
SN - 0302-9743
T2 - Intelligent Data Engineering and Automated Learning – IDEAL 2021
TI - Drift Detection in Text Data with Document Embeddings
ER -
TY - CONF
AB - Knowledge graph embedding research has mainly focused on the two smallest
normed division algebras, $\mathbb{R}$ and $\mathbb{C}$. Recent results suggest
that trilinear products of quaternion-valued embeddings can be a more effective
means to tackle link prediction. In addition, models based on convolutions on
real-valued embeddings often yield state-of-the-art results for link
prediction. In this paper, we investigate a composition of convolution
operations with hypercomplex multiplications. We propose the four approaches
QMult, OMult, ConvQ and ConvO to tackle the link prediction problem. QMult and
OMult can be considered as quaternion and octonion extensions of previous
state-of-the-art approaches, including DistMult and ComplEx. ConvQ and ConvO
build upon QMult and OMult by including convolution operations in a way
inspired by the residual learning framework. We evaluated our approaches on
seven link prediction datasets including WN18RR, FB15K-237 and YAGO3-10.
Experimental results suggest that the benefits of learning hypercomplex-valued
vector representations become more apparent as the size and complexity of the
knowledge graph grows. ConvO outperforms state-of-the-art approaches on
FB15K-237 in MRR, Hit@1 and Hit@3, while QMult, OMult, ConvQ and ConvO
outperform state-of-the-approaches on YAGO3-10 in all metrics. Results also
suggest that link prediction performances can be further improved via
prediction averaging. To foster reproducible research, we provide an
open-source implementation of approaches, including training and evaluation
scripts as well as pretrained models.
AU - Demir, Caglar
AU - Moussallem, Diego
AU - Heindorf, Stefan
AU - Ngonga Ngomo, Axel-Cyrille
ID - 29287
T2 - The 13th Asian Conference on Machine Learning, ACML 2021
TI - Convolutional Hypercomplex Embeddings for Link Prediction
ER -
TY - CONF
AU - Nickchen, Tobias
AU - Heindorf, Stefan
AU - Engels, Gregor
ID - 29294
T2 - 2021 IEEE Winter Conference on Applications of Computer Vision (WACV)
TI - Generating Physically Sound Training Data for Image Recognition of Additively Manufactured Parts
ER -
TY - GEN
AU - Heindorf, Stefan
ID - 33733
TI - Automatically generating instructions from tutorials for search and user navigation
ER -
TY - JOUR
AB - We demonstrate the integration of amorphous tungsten silicide superconducting nanowire single-photon detectors on titanium in-diffused lithium niobate waveguides. We show proof-of-principle detection of evanescently coupled photons of 1550 nm wavelength using bidirectional waveguide coupling for two orthogonal polarization directions. We investigate the internal detection efficiency as well as detector absorption using coupling-independent characterization measurements. Furthermore, we describe strategies to improve the yield and efficiency of these devices.
AU - Höpker, Jan Philipp
AU - Verma, Varun B
AU - Protte, Maximilian
AU - Ricken, Raimund
AU - Quiring, Viktor
AU - Eigner, Christof
AU - Ebers, Lena
AU - Hammer, Manfred
AU - Förstner, Jens
AU - Silberhorn, Christine
AU - Mirin, Richard P
AU - Woo Nam, Sae
AU - Bartley, Tim
ID - 23728
JF - Journal of Physics: Photonics
SN - 2515-7647
TI - Integrated superconducting nanowire single-photon detectors on titanium in-diffused lithium niobate waveguides
VL - 3
ER -
TY - JOUR
AB - While increasing digitalization enables multiple advantages for a reliable operation of technical systems, a remaining challenge in the context of condition monitoring is seen in suitable consideration of uncertainties affecting the monitored system. Therefore, a suitable prognostic approach to predict the remaining useful lifetime of complex technical systems is required. To handle different kinds of uncertainties, a novel Multi-Model-Particle Filtering-based prognostic approach is developed and evaluated by the use case of rubber-metal-elements. These elements are maintained preventively due to the strong influence of uncertainties on their behavior. In this paper, two measurement quantities are compared concerning their ability to establish a prediction of the remaining useful lifetime of the monitored elements and the influence of present uncertainties. Based on three performance indices, the results are evaluated. A comparison with predictions of a classical Particle Filter underlines the superiority of the developed Multi-Model-Particle Filter. Finally, the value of the developed method for enabling condition monitoring of technical systems related to uncertainties is given exemplary by a comparison between the preventive and the predictive maintenance strategy for the use case.
AU - Bender, Amelie
ID - 25046
IS - 10
JF - Machines
KW - prognostics
KW - RUL predictions
KW - particle filter
KW - uncertainty consideration
KW - Multi-Model-Particle Filter
KW - model-based approach
KW - rubber-metal-elements
KW - predictive maintenance
SN - 2075-1702
TI - A Multi-Model-Particle Filtering-Based Prognostic Approach to Consider Uncertainties in RUL Predictions
VL - 9
ER -
TY - GEN
AB - Network and service coordination is important to provide modern services consisting of multiple interconnected components, e.g., in 5G, network function virtualization (NFV), or cloud and edge computing. In this paper, I outline my dissertation research, which proposes six approaches to automate such network and service coordination. All approaches dynamically react to the current demand and optimize coordination for high service quality and low costs. The approaches range from centralized to distributed methods and from conventional heuristic algorithms and mixed-integer linear programs to machine learning approaches using supervised and reinforcement learning. I briefly discuss their main ideas and advantages over other state-of-the-art approaches and compare strengths and weaknesses.
AU - Schneider, Stefan Balthasar
ID - 35889
KW - nfv
KW - coordination
KW - machine learning
KW - reinforcement learning
KW - phd
KW - digest
TI - Conventional and Machine Learning Approaches for Network and Service Coordination
ER -
TY - CHAP
AU - Weber, Jutta
ED - Maurer, Kathrin
ED - Graae, Andreas Immanuel
ID - 36260
T2 - Drone Imaginaries. The Power of Remote Vision
TI - Artificial Intelligence and the Sociotechnical Imaginary: On Skynet, Self-Healing Swarms and Slaughterbots
ER -
TY - CHAP
AU - Weber, Jutta
AU - Mayer, Katja
ED - Burkhardt, Marcus
ED - Shnayien, Mary
ED - Grashöfer, Katja
ID - 36257
T2 - Explorations in Digital Cultures
TI - From Optimizing Military Operations to Targeting Terrorist Networks: Social Network Analysis in Data-Driven Warfare
ER -
TY - CHAP
AU - Weber, Jutta
ED - Braun, Kathrin
ED - Kropp, Cordula
ID - 36256
T2 - In digitaler Gesellschaft. Neukonfigurationen zwischen Robotern, Algorithmen und Usern
TI - Human-Machine Learning und Digital Commons
ER -
TY - JOUR
AB - Due to the Corona crisis, German Higher Education Institutions had to close their campuses in March and lecturers had to teach online. To understand how the Corona crisis affected students, first this article explains the structural and social inequalities in the German higher education system, using Tinto's (1975; 1997) student engagement theory. Second, the concept of Bergman-Rosamond et al. (2020) is used to analyze the challenges that Corona has raised for students, including current surveys. We found that the closure of the social space campus (and the Corona crisis as a whole) particularly hit hard those students who had previously been affected by (intersectional) inequality. Therefore, to lessen the specific challenges associated with the ad hoc transition to digital studying, the creation of a digital community of learning can help. We demonstrate how such a community can be created by the example seminar, "Digital practices: an autoethnographic observation". During the seminar, students recorded their digital technology use in a journal, and we analyzed the diary entries using the collaborate autoethnography method. The seminar example shows that this method is well suited for the development of a community of learning as it not only places students in the spotlight but as students work together on a topic they get to know each other, and a basis of trust is created through peer-feedback. Therefore, it was important to have a digital space (in this case Mahara) where the exchange could take place. The continuous insight into the students’ "learning status" enabled the lecturer to promote the learning and provide individual assistance for the students.
AU - Steinhardt, Isabel
ID - 36545
IS - 1
JF - ISA Pedagogy Series
KW - Intersectionality
KW - inequality
KW - gender
KW - diversity
KW - higher-education
KW - crisis
TI - Students in the spotlight: Using collaborative autoethnography to build a community of learning in the Corona crisis
VL - 1
ER -
TY - GEN
AB - The call for free access to research data and materials is becoming louder and louder from the political and scientific communities in Germany. More and more researchers are facing demands to open up qualitative research data for scientific purposes. They often have a general interest in sharing their data, but are unsure how to proceed. This handout was developed to provide an initial introduction to opening and sharing qualitative data. It was developed at a workshop held in Berlin in January 2020, organized by the research group „Digitization of Science“ of the Weizenbaum Institute, together with its associate researcher Dr. Isabel Steinhardt from the University of Kassel. The workshop involved staff from German research data centers as well as mentees and mentors from the Fellow Program Open Science who already have experience with Open Science, qualitative research, and interdisciplinary research. The handout is addressed primarily to qualitatively researching scientists in Germany. For this reason, it was initially written in German. One year later, we have now decided to translate the handout into English as well. The reasons are twofold: first, we want to make it accessible to researchers in Germany with little knowledge of German. Second, we also want to give interested people outside Germany an insight into the German system and the German discussion about opening up and sharing qualitative data. Due to the objectives and the history of its development, the handout focuses on the German context. This includes the literature references and further sources, and the references to research data centers as well as legal issues. We have deliberately not included a contextualization of the German situation in international discussions in order to keep the handout as short as possible.
AU - Steinhardt, Isabel
AU - Fischer, Caroline
AU - Heimstädt, Maximilian
AU - Hirsbrunner, Simon David
AU - Ikiz-Akinci, Dilek
AU - Kressin, Lisa
AU - Kretzer, Susanne
AU - Möllenkamp, Andreas
AU - Portzelt, Maike
AU - Rahal, Rima-Maria
AU - Schimmler, Sonja
AU - Wilke, René
AU - Wünsche, Hannes
ID - 36551
TI - Opening up and Sharing Data from Qualitative Research: A Primer
VL - 17
ER -
TY - CHAP
AB - Anhand einer explorativen Studie in den Fächern Jura und Soziale Arbeit wird rekonstruiert welche Praktiken Studierende in Bezug auf digitale Technologien haben und ob digitale Praktiken im Studium existieren. Dazu wurden narrative Interviews mit sechs Studierenden geführt, die habitushermeneutisch ausgewertet wurden. Die Ergebnisse zeigen keine digitalen Praktiken in Bezug auf das Studium, wohingegen sich digitale Praktiken im alltäglichen Leben zeigen. Für das Studium zeigen sich unterschiedliche Praktiken in der Nutzung digitaler Technologien, die in Beziehung zu den Kapitalsorten stehen, die Studierende besitzen. Die explorativen Ergebnisse legen nahe, dass Studierende unterschiedliche Hilfestellungen in Bezug auf die Digitalisierung des Studiums benötigen, die in der Lehrplanung und -pädagogik berücksichtigt werden müssten.
AU - Steinhardt, Isabel
ED - Bremer, Helmut
ED - Lange-Vester, Andrea
ID - 36557
SN - 978-3-7799-5861-1
T2 - Entwicklungen im Feld der Hochschule
TI - Digitale Praktiken und das Studium
ER -
TY - THES
AU - Wembe Moafo, Boris Edgar
ID - 33872
TI - Geometric and Numerical Methods in Optimal Control and Zermelo Problems on Revolution Surfaces - Applications
ER -
TY - JOUR
AB - AbstractIn order to reduce fuel consumption and thus pollutant emissions, the automotive industry is increasingly developing lightweight construction concepts that are accompanied by an increasing usage of aluminum materials. Due to poor weldability of aluminum in combination with other materials, mechanical joining methods such as clinching were developed and established in series production. In order to predict the relevant characteristics of clinched joints and to ensure the reliability of the process, it is simulated numerically during product development processes. In this regard, the predictive accuracy of the simulated process highly depends on the implemented friction model. In particular, the frictional behavior between the sheet metals as well as between the sheet metal and clinching tools has a significant impact on the geometrical formation of the clinched joint. No testing methods exist that can sufficiently investigate the frictional behavior in sheet materials, especially under high interface pressures, different relative velocities, and long friction paths, while allowing a decoupled consideration of the test parameters. This paper describes the development of further testing concepts based on a proven tribo-torsion test method for determining friction coefficients between sheet metal materials for the simulation of clinching processes. For this purpose, the correlation of interface pressure and the relative velocity between aluminum and steel sheet material in clinching processes is investigated using numerical simulation. Based on these findings, the developed concepts focus on determining friction coefficients at interface pressures of the above materials, yield stress, as well as the reproduction of the occurring friction conditions between sheet metal materials and tool surfaces in clinching processes using tool substitutes. Furthermore, wear investigations between sheet metal material and tool surface were carried out in the friction tests with subsequent EDX analyses of the frictioned tool surfaces. The developed method also allows an optical deformation measurement of the sheet metal material specimen by means of digital image correlation (DIC). Based on a methodological approach, the test setups and the test systems used are explained, and the functionality of the concepts is proven by experimental tests using different sheet metal materials.
AU - Böhnke, Max
AU - Rossel, Moritz Sebastian
AU - Bielak, Christian Roman
AU - Bobbert, Mathias
AU - Meschut, Gerson
ID - 25556
JF - The International Journal of Advanced Manufacturing Technology
SN - 0268-3768
TI - Concept development of a method for identifying friction coefficients for the numerical simulation of clinching processes
ER -
TY - GEN
AU - Weber, Jutta
ED - Elliott, Anthony
ID - 37504
T2 - Routledge Social Science Handbook of Artificial Intelligence
TI - Artificial Intelligence in the Age of Technoscience
ER -
TY - JOUR
AB - Research on technological educationininterdisciplinary scienceand socialstudies (Sachunterricht) in German primary schools emphasizes that childrenare generally interested in technology. While several STEAM initiatives point towards a growing recognition of technological literacy, the consideration of technology education ininterdisciplinaryscience and social studies is quite underrepresented in practice as well as in research and teacher training.Takinginto accountthe UN-CRPDclaims foran inclusive educational system andthus alsothe right to equally participate in a free society,participation in society through participation in technological development is a fundamental common goal of technological and inclusive education and part of widely recognized technological literacy.It is therefore not well understood how teaching and learning arrangementscan consider and satisfythe needs of all different students. The research project the present paper is part of tries to unveil the appearance of student’s basic needs in relation to technological educationfor all children. Thisinitial quantitative part of a grounded theory study examined the subjective significance of basic psychological needs in interdisciplinary science studies in primary educationto allow for a well-reasoned sample choice for subsequent interviews. Quantitative results point towards some revisions regarding the instrument used and several implications on the diversity of students ́needs in science and social studies. Future research is needed with larger samples for factor-analysis.
AU - Schröer, Franz
AU - Tenberge, Claudia
ID - 37644
IS - 2
JF - TECHNE SERIES - Forskning i slöjdpedagogik och slöjdvetenskap
KW - Inclusion
KW - basic needs
KW - Technology Education
KW - Primary Education
KW - autonomy
KW - competence
KW - social relatedness
SN - 1893-1774
TI - Technological and Inclusive Education - Considering Students’ Needs Towards Technological Learning in Primary Schools
VL - 28
ER -
TY - CHAP
AU - Alpsancar, Suzana
ED - Sprenger, Florian
ID - 34567
SN - 2702-8852
T2 - Autonome Autos – Die Zukunft des Verkehrs und die Dispositive der Mobilität
TI - „Vom Fahr-Zeug zum Fahr-Ding. Ein Heideggerianischer Kommentar zum autonomen Automobil“
ER -
TY - CONF
AU - Itner, D.
AU - Gravenkamp, H.
AU - Dreiling, Dmitrij
AU - Feldmann, Nadine
AU - Henning, Bernd
ID - 40541
T2 - 14th WCCM-ECCOMAS Congress
TI - Simulation of Guided Waves in Cylinders Subject to Arbitrary Boundary Conditions Using the Scaled Boundary Finite Element Method
VL - 700
ER -
TY - JOUR
AU - Uppenkamp, Vera
AU - Höger, Christian
ID - 41427
IS - 2
JF - Theo-Web. Zeitschrift für Religionspädagogik
TI - "Wenn sich die Mitte auflöst...", ist das kein Verlust für die Religionspädagogik - ein bilanzierender Tagungsrückblick mit Augenzwinkern
VL - 20
ER -
TY - GEN
AU - Uppenkamp, Vera
ID - 41425
T2 - Das wissenschaftlich-religionspädagogische Lexikon im Internet www.wirelex.de
TI - Art. Mädchen/Frauen
ER -
TY - THES
AU - Olma, Simon
ID - 42070
SN - 9783947647231
TI - Systemtheorie von Hardware-in-the-Loop-Simulationen mit Anwendung auf einem Fahrzeugachsprüfstand mit parallelkinematischem Lastsimulator
VL - 404
ER -
TY - THES
AU - Lankeit, Christopher
ID - 42069
TI - Systematik zur Evolution technischer Anforderungen
ER -
TY - BOOK
AU - Eckel, Julia
ID - 42250
SN - 978-3-8394-5320-9
TI - Das Audioviduum. Eine Theoriegeschichte des Menschenmotivs in audiovisuellen Medien
ER -
TY - CHAP
AU - Fuchs, Christian
ED - Fuchs, Christian
ED - Unterberger, Klaus
ID - 38153
T2 - The Public Service Media and Public Service Internet Manifesto
TI - The Public Service Media and Public Service Internet Utopias Survey Report
ER -
TY - JOUR
AU - Fuchs, Christian
ID - 38143
IS - 15
JF - Information, Communication and Society
TI - History and Class Consciousness 2.0: Georg Lukács in the Age of Digital Capitalism and Big Data
VL - 24
ER -
TY - JOUR
AU - Fuchs, Christian
ID - 38146
IS - 1
JF - tripleC: Communication, Capitalism & Critique
TI - Engels@200: Friedrich Engels and Digital Capitalism. How Relevant Are Engels’s Works 200 Years After His Birth?
VL - 19
ER -
TY - JOUR
AU - Fuchs, Christian
ID - 38145
IS - 1
JF - tripleC: Communication, Capitalism & Critique
TI - Engels@200: Friedrich Engels in the Age of Digital Capitalism. Introduction
VL - 19
ER -
TY - JOUR
AU - Fuchs, Christian
ID - 38147
IS - 7-8
JF - Critical Sociology
TI - Cornel West and Marxist Humanism
VL - 47
ER -
TY - BOOK
ED - Fuchs, Christian
ED - Unterberger, Klaus
ID - 38133
TI - The Public Service Media and Public Service Internet Manifesto
ER -
TY - CHAP
AU - Alessandro, D'Arma
AU - Fuchs, Christian
AU - Horowitz, Minna
AU - Unterberger, Klaus
ED - Fuchs, Christian
ED - Unterberger, Klaus
ID - 38152
T2 - The Public Service Media and Public Service Internet Manifesto
TI - The Future of Public Service Media and the Internet
ER -
TY - CHAP
AU - Fuchs, Christian
AU - Unterberger, Klaus
ED - Fuchs, Christian
ED - Unterberger, Klaus
ID - 38154
T2 - The Public Service Media and Public Service Internet Manifesto
TI - Introduction
ER -
TY - JOUR
AU - Fuchs, Christian
ID - 38148
IS - 1
JF - Westminster Papers in Communication and Culture
TI - The Digital Commons and the Digital Public Sphere: How to Advance Digital Democracy Today
VL - 16
ER -
TY - JOUR
AU - Fuchs, Christian
ID - 38157
IS - 1
JF - tripleC: Communication, Capitalism & Critique
TI - How Did Donald Trump Incite a Coup Attempt?
VL - 19
ER -
TY - JOUR
AU - Fuchs, Christian
ID - 38149
IS - 4
JF - Journal of Media Ethics
TI - Foundations of Communication/Media/Digital (In)Justice
VL - 36
ER -
TY - GEN
AU - Fuchs, Christian
ID - 38156
T2 - The Conversation
TI - Channel 4: Rather Than Privatising Public Service Media We Should Be Expanding It Online
ER -
TY - JOUR
AU - Fuchs, Christian
ID - 42483
IS - 2
JF - tripleC: Communication, Capitalism & Critique
TI - Preface: Manfred Knoche’s Critique of the Political Economy of the Media and Communication [Preface to the article “Media Concentration” by Manfred Knoche]
VL - 19
ER -
TY - JOUR
AB - Lithium niobate (LiNbO3), a material frequently used in optical applications, hosts different kinds of polarons that significantly affect many of its physical properties. In this study, a variety of electron polarons, namely free, bound, and bipolarons, are analyzed using first-principles calculations. We perform a full structural optimization based on density-functional theory for selected intrinsic defects with special attention to the role of symmetry-breaking distortions that lower the total energy. The cations hosting the various polarons relax to a different degree, with a larger relaxation corresponding to a larger gap between the defect level and the conduction-band edge. The projected density of states reveals that the polaron states are formerly empty Nb 4d states lowered into the band gap. Optical absorption spectra are derived within the independent-particle approximation, corrected by the GW approximation that yields a wider band gap and by including excitonic effects within the Bethe-Salpeter equation. Comparing the calculated spectra with the density of states, we find that the defect peak observed in the optical absorption stems from transitions between the defect level and a continuum of empty Nb 4d states. Signatures of polarons are further analyzed in the reflectivity and other experimentally measurable optical coefficients.
AU - Schmidt, Falko
AU - Kozub, Agnieszka L.
AU - Gerstmann, Uwe
AU - Schmidt, Wolf Gero
AU - Schindlmayr, Arno
ID - 21946
JF - Crystals
TI - Electron polarons in lithium niobate: Charge localization, lattice deformation, and optical response
VL - 11
ER -
TY - JOUR
AB - Tailor-made ordered mesoporous materials bear great potential in numerous fields of application where large interfaces are required. However, the inherent surfacechemical properties of conventional materials, such as silica, carbon or organosilica, poses some limitations with respect to their application. Surface manipulation by functionalization with chemically more reactive groups is one way to improve materials for their desired purpose. Another approach is the design of high surface-area composite materials. The surface manipulation, either by functionalization or by introducing guest species, can be performed selectively. This means that when several distinct, i.e. , hierarchical, types of surfaces or pore systems exist in a material, each of them may be chosen for manipulation. Several strategies can be identified to achieve this goal. Molecules or molecule assemblies can be utilized to temporarily protect pores or surfaces (soft protection), while manipulation occurs at the accessible sites. This approach is a recurring motive in this review and can also be applied to rigid template matrices (hard protection). Furthermore, the size of functionalization agents (size protection) and their reactivity/diffusion (kinetic protection) into the pores can also be utilized to achieve selectivity. In addition, challenges in the synthesis and characterization of selectively manipulated ordered mesoporous materials are discussed.
AU - Tiemann, Michael
AU - Weinberger, Christian
ID - 25893
JF - Advanced Materials Interfaces
SN - 2196-7350
TI - Selective Modification of Hierarchical Pores and Surfaces in Nanoporous Materials
ER -
TY - JOUR
AU - Fuchs, Christian
ID - 41431
IS - 1
JF - tripleC: Communication, Capitalism & Critique
TI - Engels@200: Friedrich Engels in the Age of Digital Capitalism
VL - 19
ER -
TY - JOUR
AU - Möhring, Julia
AU - Krumhöfner, Anika
AU - Gräfin von Plettenberg, Elisabeth Gudila Sophia Ida Maria
ID - 43016
JF - -
TI - Bewegungsförderung in Ganztagsschulen
ER -
TY - GEN
AU - Leineweber, Jonas
ID - 33210
TI - Veranstaltungsbericht: Immaterielles Kulturerbe in Nordrhein-Westfalen – Steigerlied und Trinkhallenkultur im Ruhrgebiet erhalten Auszeichnung anlässlich der Neuaufnahmen in das nordrhein-westfälische Landesinventar
ER -
TY - GEN
AU - Leineweber, Jonas
ID - 33209
TI - Tagungsbericht: Immaterielles Kulturerbe und regionale Identität. Gesellschaftliche Repräsentation und Partizipation im Schützenwesen
ER -
TY - JOUR
AB - We perform a theoretical analysis of the structural and electronic properties of sodium potassium niobate K1-xNaxNbO3 in the orthorhombic room-temperature phase, based on density-functional theory in combination with the supercell approach. Our results for x=0 and x=0.5 are in very good agreement with experimental measurements and establish that the lattice parameters decrease linearly with increasing Na contents, disproving earlier theoretical studies based on the virtual-crystal approximation that claimed a highly nonlinear behavior with a significant structural distortion and volume reduction in K0.5Na0.5NbO3 compared to both end members of the solid solution. Furthermore, we find that the electronic band gap varies very little between x=0 and x=0.5, reflecting the small changes in the lattice parameters.
AU - Bidaraguppe Ramesh, Nithin
AU - Schmidt, Falko
AU - Schindlmayr, Arno
ID - 22960
IS - 8
JF - The European Physical Journal B
SN - 1434-6028
TI - Lattice parameters and electronic band gap of orthorhombic potassium sodium niobate K0.5Na0.5NbO3 from density-functional theory
VL - 94
ER -
TY - JOUR
AU - Friedrich, Christoph
AU - Blügel, Stefan
AU - Schindlmayr, Arno
ID - 22761
IS - 3
JF - Physical Review B
SN - 2469-9950
TI - Erratum: Efficient implementation of the GW approximation within the all-electron FLAPW method [Phys. Rev. B 81, 125102 (2010)]
VL - 104
ER -
TY - JOUR
AB - Employing the ultrafast control of electronic states of a semiconductor quantum dot in a cavity, we introduce an approach to achieve on-demand emission of single photons with almost perfect indistinguishability and photon pairs with near ideal entanglement. Our scheme is based on optical excitation off resonant to a cavity mode followed by ultrafast control of the electronic states using the time-dependent quantum-confined Stark effect, which then allows for cavity-resonant emission. Our theoretical analysis considers cavity-loss mechanisms, the Stark effect, and phonon-induced dephasing, allowing realistic predictions for finite temperatures.
AU - Bauch, David
AU - Heinze, Dirk Florian
AU - Förstner, Jens
AU - Jöns, Klaus
AU - Schumacher, Stefan
ID - 23816
JF - Physical Review B
KW - tet_topic_qd
SN - 2469-9950
TI - Ultrafast electric control of cavity mediated single-photon and photon-pair generation with semiconductor quantum dots
VL - 104
ER -
TY - JOUR
AB - Density-functional theory within a Berry-phase formulation of the dynamical polarization is used to determine the second-order susceptibility χ(2) of lithium niobate (LiNbO3). Defect trapped polarons and bipolarons are found to strongly enhance the nonlinear susceptibility of the material, in particular if localized at NbV–VLi defect pairs. This is essentially a consequence of the polaronic excitation resulting in relaxation-induced gap states. The occupation of these levels leads to strongly enhanced χ(2) coefficients and allows for the spatial and transient modification of the second-harmonic generation of macroscopic samples.
AU - Kozub, Agnieszka L.
AU - Schindlmayr, Arno
AU - Gerstmann, Uwe
AU - Schmidt, Wolf Gero
ID - 23418
JF - Physical Review B
SN - 2469-9950
TI - Polaronic enhancement of second-harmonic generation in lithium niobate
VL - 104
ER -
TY - JOUR
AU - Martin, Sven
AU - Tröster, Thomas
ID - 24548
JF - ESAFORM 2021
TI - Joint point loadings in car bodies – the influence of manufacturing tolerances and scatter in material properties
ER -