scispace - formally typeset
Search or ask a question
Institution

University of Paderborn

EducationPaderborn, Nordrhein-Westfalen, Germany
About: University of Paderborn is a education organization based out in Paderborn, Nordrhein-Westfalen, Germany. It is known for research contribution in the topics: Control reconfiguration & Software. The organization has 6684 authors who have published 16929 publications receiving 323154 citations.


Papers
More filters
Journal ArticleDOI
TL;DR: In this article, the design of nonlinear photonic metasurfaces is discussed, in particular the criteria for choosing the materials and symmetries of the meta-atoms.
Abstract: Compared with conventional optical elements, 2D photonic metasurfaces, consisting of arrays of antennas with subwavelength thickness (the ‘meta-atoms’), enable the manipulation of light–matter interactions on more compact platforms. The use of metasurfaces with spatially varying arrangements of meta-atoms that have subwavelength lateral resolution allows control of the polarization, phase and amplitude of light. Many exotic phenomena have been successfully demonstrated in linear optics; however, to meet the growing demand for the integration of more functionalities into a single optoelectronic circuit, the tailorable nonlinear optical properties of metasurfaces will also need to be exploited. In this Review, we discuss the design of nonlinear photonic metasurfaces — in particular, the criteria for choosing the materials and symmetries of the meta-atoms — for the realization of nonlinear optical chirality, nonlinear geometric Berry phase and nonlinear wavefront engineering. Finally, we survey the application of nonlinear photonic metasurfaces in optical switching and modulation, and we conclude with an outlook on their use for terahertz nonlinear optics and quantum information processing. Photonic metasurfaces can be used to control the polarization, phase and amplitude of light. Nonlinear metasurfaces enable giant nonlinear optical chirality, realization of the geometric Berry phase, wavefront engineering, and optical switching and modulation, and hold potential for on-chip applications.

542 citations

Journal ArticleDOI
TL;DR: Elstner et al. as mentioned in this paper proposed a self-consistent redistribution of Mulliken charges (SCC) approach to approximate the Kohn-Sham total energy in density functional theory with respect to charge density fluctuations.
Abstract: We outline recent developments in quantum mechanical atomistic modelling of complex materials properties that combine the efficiency of semi-empirical quantum-chemistry and tight-binding approaches with the accuracy and transferability of more sophisticated density-functional and post-Hartree-Fock methods with the aim to perform highly predictive materials simulations of technological relevant sizes in physics, chemistry and biology. Following Harris, Foulkes and Haydock, the methods are based on an expansion of the Kohn-Sham total energy in density-functional theory (DFT) with respect to charge density fluctuations at a given reference density. While the zeroth order approach is equivalent to a common standard non-self-consistent tight-binding (TB) scheme, at second order by variationally treating the approximate Kohn-Sham energy a transparent, parameter-free, and readily calculable expression for generalized Hamiltonian matrix elements may be derived. These matrix elements are modified by a Self-Consistent redistribution of Mulliken Charges (SCC). Besides the usual “band-structure” and short-range repulsive terms the final approximate Kohn-Sham energy explicitly includes Coulomb interaction between charge fluctuations. The new SCC-scheme is shown to successfully apply to problems, where defficiencies within the non-SCC standard TB-approach become obvious. These cover defect calculations and surface studies in polar semiconductors (see M. Haugk et al. of this special issue), spectroscopic studies of organic light-emitting thin films, briefly outlined in the present article, and atomistic investigations of biomolecules (see M. Elstner et al. of this special issue).

541 citations

Journal ArticleDOI
TL;DR: A thorough overview of modern noise-robust techniques for ASR developed over the past 30 years is provided and methods that are proven to be successful and that are likely to sustain or expand their future applicability are emphasized.
Abstract: New waves of consumer-centric applications, such as voice search and voice interaction with mobile devices and home entertainment systems, increasingly require automatic speech recognition (ASR) to be robust to the full range of real-world noise and other acoustic distorting conditions. Despite its practical importance, however, the inherent links between and distinctions among the myriad of methods for noise-robust ASR have yet to be carefully studied in order to advance the field further. To this end, it is critical to establish a solid, consistent, and common mathematical foundation for noise-robust ASR, which is lacking at present. This article is intended to fill this gap and to provide a thorough overview of modern noise-robust techniques for ASR developed over the past 30 years. We emphasize methods that are proven to be successful and that are likely to sustain or expand their future applicability. We distill key insights from our comprehensive overview in this field and take a fresh look at a few old problems, which nevertheless are still highly relevant today. Specifically, we have analyzed and categorized a wide range of noise-robust techniques using five different criteria: 1) feature-domain vs. model-domain processing, 2) the use of prior knowledge about the acoustic environment distortion, 3) the use of explicit environment-distortion models, 4) deterministic vs. uncertainty processing, and 5) the use of acoustic models trained jointly with the same feature enhancement or model adaptation process used in the testing stage. With this taxonomy-oriented review, we equip the reader with the insight to choose among techniques and with the awareness of the performance-complexity tradeoffs. The pros and cons of using different noise-robust ASR techniques in practical application scenarios are provided as a guide to interested practitioners. The current challenges and future research directions in this field is also carefully analyzed.

534 citations

Journal ArticleDOI
TL;DR: This review summarizes the basic aspects of materials synthesis, discusses some structural properties relevant in gas sensing, and gives an overview of the literature on ordered mesoporous gas sensors.
Abstract: Ordered mesoporous materials have great potential in the field of gas sensing. Today various template-assisted synthesis methods facilitate the preparation of silica (SiO2) as well as numerous metal oxides with well-defined, uniform and regular pore systems. The unique nanostructural properties of such materials are particularly useful for their application as active layers in gas sensors based on various operating principles, such as capacitive, resistive, or optical sensing. This review summarizes the basic aspects of materials synthesis, discusses some structural properties relevant in gas sensing, and gives an overview of the literature on ordered mesoporous gas sensors.

534 citations

Journal ArticleDOI
TL;DR: In this paper, coupled chemotaxis (Navier and Stokes) systems generalizing the prototype have been proposed to describe the collective effects arising in bacterial suspensions in fluid drops, and they have been applied to the model of collective effects of bacterial suspensions.
Abstract: In the modeling of collective effects arising in bacterial suspensions in fluid drops, coupled chemotaxis-(Navier–)Stokes systems generalizing the prototype have been proposed to describe the spont

523 citations


Authors

Showing all 6872 results

NameH-indexPapersCitations
Martin Karplus163831138492
Marco Dorigo10565791418
Robert W. Boyd98116137321
Thomas Heine8442324210
Satoru Miyano8481138723
Wen-Xiu Ma8342020702
Jörg Neugebauer8149130909
Thomas Lengauer8047734430
Gotthard Seifert8044526136
Reshef Tenne7452924717
Tim Meyer7454824784
Qiang Cui7129220655
Thomas Frauenheim7045117887
Walter Richtering6733214866
Marcus Elstner6720918960
Network Information
Related Institutions (5)
Eindhoven University of Technology
52.9K papers, 1.5M citations

95% related

Royal Institute of Technology
68.4K papers, 1.9M citations

93% related

Karlsruhe Institute of Technology
82.1K papers, 2.1M citations

93% related

École Polytechnique Fédérale de Lausanne
98.2K papers, 4.3M citations

91% related

Carnegie Mellon University
104.3K papers, 5.9M citations

91% related

Performance
Metrics
No. of papers from the Institution in previous years
YearPapers
2023131
2022242
20211,030
20201,010
2019948
2018967