Refine
Year of publication
- 2015 (32) (remove)
Document Type
- Article (32) (remove)
Has Fulltext
- no (32)
Is part of the Bibliography
- no (32)
Keywords
- Humans (2)
- ADHESION (1)
- APPROXIMATION (1)
- ARRAYS (1)
- Acid base balance (1)
- Adhesive bonding (1)
- Aged, 80 and over (1)
- Arbeitstakt (1)
- Arbitrary Lagrangian-Eulerian (1)
- Automation (1)
Institute
- Fakultät Maschinenbau (13)
- Fakultät Elektro- und Informationstechnik (6)
- Fakultät Informatik und Mathematik (5)
- Fakultät Angewandte Natur- und Kulturwissenschaften (4)
- Fakultät Angewandte Sozial- und Gesundheitswissenschaften (3)
- Regensburg Center of Biomedical Engineering - RCBE (3)
- Labor Bauphysik (2)
- Labor Biomechanik (LBM) (2)
- Labor Innovation & Regulatory Affairs (IRA) (2)
- Labor Intelligente Materialien und Strukturen (2)
Begutachtungsstatus
- peer-reviewed (32) (remove)
We compute the Fourier expansion of Hecke operators on vector-valued modular forms for the Weil representation associated to a lattice L. The Hecke operators considered in this paper include operators T(p^2l) where p is a prime dividing the level of the lattice L. Additionally, an explicit formula for a general type of Gauss sum associated to a lattice L drops out as a by-product.
EMDLAB: A toolbox for analysis of single-trial EEG dynamics using empirical mode decomposition
(2015)
Background:
Empirical mode decomposition (EMD) is an empirical data decomposition technique. Recently there is growing interest in applying EMD in the biomedical field.
New method:
EMDLAB is an extensible plug-in for the EEGLAB toolbox, which is an open software environment for electrophysiological data analysis.
Results:
EMDLAB can be used to perform, easily and effectively, four common types of EMD: plain EMD, ensemble EMD (EEMD), weighted sliding EMD (wSEMD) and multivariate EMD (MEMD) on EEG data. In addition, EMDLAB is a user-friendly toolbox and closely implemented in the EEGLAB toolbox.
Comparison with existing methods:
EMDLAB gains an advantage over other open-source toolboxes by exploiting the advantageous visualization capabilities of EEGLAB for extracted intrinsic mode functions (IMFs) and Event-Related Modes (ERMs) of the signal.
Conclusions:
EMDLAB is a reliable, efficient, and automated solution for extracting and visualizing the extracted IMFs and ERMs by EMD algorithms in EEG study.
PURPOSE
Reconstruction of x-ray computed tomography (CT) data remains a mathematically challenging problem in medical imaging. Complementing the standard analytical reconstruction methods, sparse regularization is growing in importance, as it allows inclusion of prior knowledge. The paper presents a method for sparse regularization based on the curvelet frame for the application to iterative reconstruction in x-ray computed tomography.
METHODS
In this work, the authors present an iterative reconstruction approach based on the alternating direction method of multipliers using curvelet sparse regularization.
RESULTS
Evaluation of the method is performed on a specifically crafted numerical phantom dataset to highlight the method's strengths. Additional evaluation is performed on two real datasets from commercial scanners with different noise characteristics, a clinical bone sample acquired in a micro-CT and a human abdomen scanned in a diagnostic CT. The results clearly illustrate that curvelet sparse regularization has characteristic strengths. In particular, it improves the restoration and resolution of highly directional, high contrast features with smooth contrast variations. The authors also compare this approach to the popular technique of total variation and to traditional filtered backprojection.
CONCLUSIONS
The authors conclude that curvelet sparse regularization is able to improve reconstruction quality by reducing noise while preserving highly directional features.
Steigende Fallzahlen von Menschen mit Demenz, der komplexe Bedarf und eine unzureichende Versorgungsrealität erfordern innovative und nachhaltige Lösungsansätze. Der Beitrag stellt ein Versorgungsmodell für Menschen mit Demenz vor, das infolge akuter Versorgungsprobleme entwickelt wurde und das eine umfassende, patientenorientierte Versorgung über Sektorengrenzen hinweg umsetzt. Beschrieben werden Struktur und Bedingungen gelingender Kooperation und umfassender Versorgung.
Artifacts in Incomplete Data Tomography with Applications to Photoacoustic Tomography and Sonar
(2015)
We develop a paradigm using microlocal analysis that allows one to characterize the visible and added singularities in a broad range of incomplete data tomography problems. We give precise characterizations for photoacoustic and thermoacoustic tomography and sonar, and provide artifact reduction strategies. In particular, our theorems show that it is better to arrange sonar detectors so that the boundary of the set of detectors does not have corners and is smooth. To illustrate our results, we provide reconstructions from synthetic spherical mean data as well as from experimental photoacoustic data.
We propose a new algorithmic approach to the non-smooth and non-convex Potts problem (also called piecewise-constant Mumford–Shah problem) for inverse imaging problems. We derive a suitable splitting into specific subproblems that can all be solved efficiently. Our method does not require a priori knowledge on the gray levels nor on the number of segments of the reconstruction. Further, it avoids anisotropic artifacts such as geometric staircasing. We demonstrate the suitability of our method for joint image reconstruction and segmentation. We focus on Radon data, where we in particular consider limited data situations. For instance, our method is able to recover all segments of the Shepp–Logan phantom from seven angular views only. We illustrate the practical applicability on a real positron emission tomography dataset. As further applications, we consider spherical Radon data as well as blurred data.
In-plant milk-run systems are transportation systems, where materials are delivered from a central storage area to several points of use on defined routes and in short intervals. Milk-run systems generally enable frequent deliveries in smaller lot sizes with short lead times and low inventory at the points of use. In real milk-run systems, the number of deliveries per interval varies due to, e.g., variations in the production program. To enable efficient and stable milk-run system operations, these systems therefore must be able to cope with peaks in the number of deliveries. We develop different strategies for handling these delivery peaks and evaluate them with respect to delivery cost, lead time and service level using real material consumption data from two large companies from the automotive industry.
Purpose – The purpose of this paper is to demonstrate the processability of cohesive PE-HD particles in laser beam melting processes (LBM) of polymers. Furthermore, we present a characterization method for polymer particles, which can predict the quality of the powder deposition via LBM processes. Design/methodology/approach – This study focuses on the application of dry particle coating processes to increase flowability and bulk density of PE-HD particles. Both has been measured and afterwards validated via powder deposition of PE-HD particles in a LBM machine. Findings – For efficient coating in a dry particle coating process, the PE-HD particles and the attached nanoparticles need to show similar surface chemistry, i.e. both need to behave either hydrophobic or hydrophilic. It is demonstrated that dry particle coating is appropriate to enhance flowability and bulk density of PE-HD particles and hence considerably improves LBM processes and the resulting product quality. Originality/value – At present, in LBM processes mainly polyamide (PA), 12 particles are used, which are so far quite expensive in comparison to, for example, PE-HD particles. This work provides a unique and versatile method for nanoparticulate surface modification which may be applied to a wide variety of materials. After the coating, the particles are applicable for the LBM process. Our results provide a correlation between flowability and bulk density and the resulting product quality.
In diesem Beitrag wird eine Theorie zur taktorientierten Fertigungssteuerung entwickelt. Es wird der kleinste Repräsentant einer taktorientiert gesteuerten Werkstatt ermittelt - das Ein-Ressourcen- Modell. Durch die Modifikation des Trichtermodells kann ein allgemeingültiges Beschreibungsmodell des Produktionsprozesses bei taktorientierter Fertigungssteuerung erarbeitet werden - das taktorientierte Trichtermodell. Es ermöglicht die Darstellung der Arbeitsbestände im aktuellen Bearbeitungstakt und der des nachfolgenden Taktes. Weiter wird das taktbasierte Trichtermodell in ein taktbasiertes Durchlaufdiagramm überführt. Hiermit kann das Bestandsverhalten des Ein-Ressourcen-Modells über der Zeit dargestellt werden. Das optimale Bestandsverhalten pro Takt kann durch ein idealisiertes Durchlaufdiagramm beschrieben werden. Bei realer Auslastung der Ressource entstehen schwankende Arbeitsbestände pro Takt. Hierbei werden durch zu geringe Bestände pro Takt Auslastungsverluste an der Ressource erzeugt. Durch zu hohe Bestände pro Takt entstehen ohne Kapazitätsanpassungen Verspätungen.
Machine allocation planning in job-shop production is challenging due to the high variability of machining times. The tact-time based production control reduces planning effort also the flow of orders in the shop floor is more predictable. This article takes a deeper look at a single production unit controlled tact based. By enhancing the funnel model and looking at the stock behaviour of production units, a deeper understanding of tact-time based production control is gained.