Search

Your search keyword '"Jäkel Jens"' showing total 15 results
Start Over Author "Jäkel Jens" Search Limiters Available in Library Collection
15 results on '"Jäkel Jens"'

1. Simulation of a passive position control for ferromagnetic particles with multiple Halbach rings

Author

Thiel Robert and Jäkel Jens

Subjects
particle manipulation, magnetic nanoparticles, halbach ring, magnetic field, position control, simulatiuon, Medicine
Abstract

Various types of magnetic nanoparticles have been developed for a range of medical applications and some have the potential to treat diseases. In this paper, a new method for controlling the position of these magnetic particles by changing the magnetic field surrounding them using three Halbach ringsis investigated with the aid of a simulation. The inner ring controls the direction, and the position of the two outer rings can keep the group of particles together. In the simulation, the magnetic field is calculated analytically for each time step and the movement of the particles is simulated by applying the corresponding forces. These result from the manipulable external magnetic field, the magnetic field between the particles, the Lennard-Jones potential to model attractive interactions between the particles and the drag. In the simulation, we show how the particles are manipulated using a Levenberg-Marquard algorithm and develop a closedloop control for the position of the grouped particles by manipulating the magnetic field inside the Halbach rings by changing the angular position of these rings.

Published
2022
Full Text
View/download PDF

2. Simulation system for intraoperative neuromonitoring

Author

Thiel Robert, Haupt Peter, and Jäkel Jens

Subjects
neuromonitoring, simulation system, ent surgery, magnetic tracking, localization of nerve tracts, Medicine
Abstract

This paper presents a simulation system (“patient model”) for intraoperative neuromonitoring (IONM) applied to mastoidectomy. IONM is an electrophysiological method for monitoring the integrity and localization of nerve tracts, which helps the surgeon to avoid injuries and damage to neural risk structures (e.g. facial nerve) during surgery. To use the IONM successfully, the surgeon needs appropriate training and experience. The presented simulation system provides training possibilities in a realistic, cost-efficient and reproducible way. In the simulation system, the position of the probe during training is determined by a magnetic tracking method. Depending on the distance to the virtual nerve, a synthetic electromyogram (EMG) signal is sent to a real neuromonitor. The trainee learns to interpret the output of the neuromonitor. The trainer can choose different training scenarios, such as localization of the nerve, milling or coagulating, using a web application.

Published
2020
Full Text
View/download PDF

4. Tagungsband AALE 2023: Mit Automatisierung gegen den Klimawandel

Author

Hochschule für Technik, Wirtschaft und Kultur Leipzig, Reiff-Stephan, Jörg, Jäkel, Jens, Schwarz, André, Hochschule für Technik, Wirtschaft und Kultur Leipzig, Reiff-Stephan, Jörg, Jäkel, Jens, and Schwarz, André

Published
2023

8. Analyse und Anpassung ausgewählter Optimierungsverfahren für den Digitalen Zwilling von Verdichteranlagen

Author

Hochschule für Technik, Wirtschaft und Kultur Leipzig, Thiel, Robert, Jäkel, Jens, Schleifer, Kevin, Schulze, Rico, Hochschule für Technik, Wirtschaft und Kultur Leipzig, Thiel, Robert, Jäkel, Jens, Schleifer, Kevin, and Schulze, Rico

Abstract

Digitale Zwillinge werden in der Betriebsphase einer Maschine oder Anlage für verschiedene Fragestellungen angewendet, bspw. für die Zustandserkennung. Voraussetzung dafür ist, dass der Digitale Zwilling über Modelle des Anlagenverhaltens verfügt, die verschiedene Zustände, einschließlich von Fehlerzustände, adäquat beschreiben. Ein wesentlicher Aspekt dabei ist die Identifikation der Modellparameter. Dieser Beitrag dient der Analyse und Anpassung ausgewählter Optimierungsmethoden (gradientenbasierter Verfahren und ein Partikelschwarmoptimierer) am Beispiel von Modellen für Kompressoren und Turbinenanlagen. Dazu wird mit einem analytischen Ansatz ein Modell einer realen Kompressoranlage erstellt. Um die Qualität der Optimierungsergebnisse vergleichen zu können, wird eine Fehlermetrik eingeführt. Das Verhalten der Optimierer wird unter den folgenden realistischen Fehlerszenarien ermittelt: Fehler in den Modellparametern, Rauschen, initialer Abstand vom Optimum, fehlerhaft Messstellen (ohne und mit Detektion). Zur numerischen Bewertung der Identifizierbarkeit werden zwei Kriterien eingeführt.

Published
2022

9. Preliminary Biomechanical Evaluation of a Novel Exoskeleton Robotic System to Assist Stair Climbing

Author

Böhme, Max, Köhler, Hans-Peter, Thiel, Robert, Jäkel, Jens, Zentner, Johannes, Witt, Maren, Böhme, Max, Köhler, Hans-Peter, Thiel, Robert, Jäkel, Jens, Zentner, Johannes, and Witt, Maren

Abstract

A novel exoskeleton robotic system was developed to assist stair climbing. This active demonstrator consists of a motor with a cable system, various sensors, and a control system with a power supply. The objective of this preliminary study is a biomechanical evaluation of the novel system to determine its effectiveness in use. For this purpose, three test persons were biomechan- ically investigated, who performed stair ascents and descents with and without the exoskeleton. Kinematics, kinetics, and muscle activity of the knee extensors were measured. The measured data were biomechanically simulated in order to evaluate the characteristics of joint angles, moments, and reaction forces. The results show that the new exoskeleton assists both the ascent and the descent according to the measured surface electromyography (sEMG) signals, as the knee extensors are relieved by an average of 19.3%. In addition, differences in the interaction between the test persons and the system were found. This could be due to a slightly different operation of the assisting force or to the different influence of the system on the kinematics of the users.

Published
2022

13. A cost-sensitive learning algorithm for fuzzy rule-based classifiers

Author

Beck, Sebastian, Mikut, Ralf, and Jäkel, Jens

Subjects
Intel·ligència artificial, Algorismes computacionals, Fuzzy rules, 68 Computer science::68T Artificial intelligence [Classificació AMS]
Abstract

Designing classifiers may follow different goals. Which goal to prefer among others depends on the given cost situation and the class distribution. For example, a classifier designed for best accuracy in terms of misclassifica- tions may fail when the cost of misclassification of one class is much higher than that of the other. This paper presents a decision-theoretic extension to make fuzzy rule generation cost-sensitive. Furthermore, it will be shown how interpretability aspects and the costs of feature acquisition can be ac- counted for during classifier design. Natural language text is used to explain the generated fuzzy rules and their design process

Published
2004

15. Transcriptional profiling reveals barcode-like toxicogenomic responses in the zebrafish embryo

Author

Yang, Lixin, Kemadjou, Jules, Zinsmeister, Christian, Bauer, Matthias, Legradi, Jessica, Müller, Ferenc, Pankratz, Michael, Jäkel, Jens, and Strähle, Uwe

Abstract

Background Early life stages are generally most sensitive to toxic effects. Our knowledge on the action of manmade chemicals on the developing vertebrate embryo is, however, rather limited. We addressed the toxicogenomic response of the zebrafish embryo in a systematic manner by asking whether distinct chemicals would induce specific transcriptional profiles.Results We exposed zebrafish embryos to a range of environmental toxicants and measured the changes in gene-expression profiles by hybridizing cDNA to an oligonucleotide microarray. Several hundred genes responded significantly to at least one of the 11 toxicants tested. We obtained specific expression profiles for each of the chemicals and could predict the identity of the toxicant from the expression profiles with high probability. Changes in gene expression were observed at toxicant concentrations that did not cause morphological effects. The toxicogenomic profiles were highly stage specific and we detected tissue-specific gene responses, underscoring the sensitivity of the assay system.Conclusion Our results show that the genome of the zebrafish embryo responds to toxicant exposure in a highly sensitive and specific manner. Our work provides proof-of-principle for the use of the zebrafish embryo as a toxicogenomic model and highlights its potential for systematic, large-scale analysis of the effects of chemicals on the developing vertebrate embryo.

Published
2007
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results