The influence of hydroxyapatite-coated SPIONs on cytokine release - implications for safety and potential therapeutic use. - In: Biomedical engineering, ISSN 1862-278X, Bd. 66 (2021), S. S381
Enthalten in: 07-0900-C8
https://doi.org/10.1515/bmt-2021-6061
Multi-task near-field perception for autonomous driving using surround-view fisheye cameras. - Ilmenau : Universitätsbibliothek, 2021. - 1 Online-Ressource (xxv, 219 Seiten)
Technische Universität Ilmenau, Dissertation 2021
Literaturverzeichnis: Seite 183-219
Die Bildung der Augen führte zum Urknall der Evolution. Die Dynamik änderte sich von einem primitiven Organismus, der auf den Kontakt mit der Nahrung wartete, zu einem Organismus, der durch visuelle Sensoren gesucht wurde. Das menschliche Auge ist eine der raffiniertesten Entwicklungen der Evolution, aber es hat immer noch Mängel. Der Mensch hat über Millionen von Jahren einen biologischen Wahrnehmungsalgorithmus entwickelt, der in der Lage ist, Autos zu fahren, Maschinen zu bedienen, Flugzeuge zu steuern und Schiffe zu navigieren. Die Automatisierung dieser Fähigkeiten für Computer ist entscheidend für verschiedene Anwendungen, darunter selbstfahrende Autos, Augmented Realität und architektonische Vermessung. Die visuelle Nahfeldwahrnehmung im Kontext von selbstfahrenden Autos kann die Umgebung in einem Bereich von 0-10 Metern und 360˚ Abdeckung um das Fahrzeug herum wahrnehmen. Sie ist eine entscheidende Entscheidungskomponente bei der Entwicklung eines sichereren automatisierten Fahrens. Jüngste Fortschritte im Bereich Computer Vision und Deep Learning in Verbindung mit hochwertigen Sensoren wie Kameras und LiDARs haben ausgereifte Lösungen für die visuelle Wahrnehmung hervorgebracht. Bisher stand die Fernfeldwahrnehmung im Vordergrund. Ein weiteres wichtiges Problem ist die begrenzte Rechenleistung, die für die Entwicklung von Echtzeit-Anwendungen zur Verfügung steht. Aufgrund dieses Engpasses kommt es häufig zu einem Kompromiss zwischen Leistung und Laufzeiteffizienz. Wir konzentrieren uns auf die folgenden Themen, um diese anzugehen: 1) Entwicklung von Nahfeld-Wahrnehmungsalgorithmen mit hoher Leistung und geringer Rechenkomplexität für verschiedene visuelle Wahrnehmungsaufgaben wie geometrische und semantische Aufgaben unter Verwendung von faltbaren neuronalen Netzen. 2) Verwendung von Multi-Task-Learning zur Überwindung von Rechenengpässen durch die gemeinsame Nutzung von initialen Faltungsschichten zwischen den Aufgaben und die Entwicklung von Optimierungsstrategien, die die Aufgaben ausbalancieren.
https://doi.org/10.22032/dbt.50751
Kraftmessung von Elektroden an einem menschlichen Kopfmodell :
Force measurement of electrodes on a human head model. - In: Technisches Messen, ISSN 2196-7113, Bd. 88 (2021), 11, S. 724-730
Electroencephalography (EEG) and transcranial electric stimulation (TES) require caps for holding the respective electrodes in place. To support the optimal design of such caps, knowledge of the force-displacement curves for each electrode position is desirable. We propose a calibrated setup to traceably measure force-displacement curves which consists of a human head model, a force sensor, a linear guide, a stepper motor, and a multiplexing multimeter. Repeated measures of a textile EEG-cap and a TES-cap show significant non-linearity and hysteresis effects for the force-displacement curves. Our setup will allow for the assessment of the fit of EEG and TES-caps for various head shapes and sizes.
https://doi.org/10.1515/teme-2021-0082
3D retinal imaging and measurement using light field technology. - In: Journal of biomedical optics, ISSN 1560-2281, Bd. 26 (2021), 12, S. 126002-1-126002-19
Significance: Light-field fundus photography has the potential to be a new milestone in ophthalmology. Up-to-date publications show only unsatisfactory image quality, preventing the use of depth measurements. We show that good image quality and, consequently, reliable depth measurements are possible, and we investigate the current challenges of this novel technology. Aim: We investigated whether light field (LF) imaging of the retina provides depth information, on which structures the depth is estimated, which illumination wavelength should be used, whether deeper layers are measurable, and what kinds of artifacts occur. Approach: The technical setup, a mydriatic fundus camera with an LF imager, and depth estimation were validated by an eye model and in vivo measurements of three healthy subjects and three subjects with suspected glaucoma. Comparisons between subjects and the corresponding optical coherence tomography (OCT) measurements were used for verification of the depth estimation. Results: This LF setup allowed for three-dimensional one-shot imaging and depth estimation of the optic disc with green light. In addition, a linear relationship was found between the depth estimates of the OCT and those of the setup developed here. This result is supported by the eye model study. Deeper layers were not measurable. Conclusions: If image artifacts can be handled, LF technology has the potential to help diagnose and monitor glaucoma risk at an early stage through a rapid, cost-effective one-shot technology.
https://doi.org/10.1117/1.JBO.26.12.126002
Me-doped Ti-Me intermetallic thin films used for dry biopotential electrodes: a comparative case study. - In: Sensors, ISSN 1424-8220, Bd. 21 (2021), 23, 8143, S. 1-17
In a new era for digital health, dry electrodes for biopotential measurement enable the monitoring of essential vital functions outside of specialized healthcare centers. In this paper, a new type of nanostructured titanium-based thin film is proposed, revealing improved biopotential sensing performance and overcoming several of the limitations of conventional gel-based electrodes such as reusability, durability, biocompatibility, and comfort. The thin films were deposited on stainless steel (SS) discs and polyurethane (PU) substrates to be used as dry electrodes, for non-invasive monitoring of body surface biopotentials. Four different Ti-Me (Me = Al, Cu, Ag, or Au) metallic binary systems were prepared by magnetron sputtering. The morphology of the resulting Ti-Me systems was found to be dependent on the chemical composition of the films, specifically on the type and amount of Me. The existence of crystalline intermetallic phases or glassy amorphous structures also revealed a strong influence on the morphological features developed by the different systems. The electrodes were tested in an in-vivo study on 20 volunteers during sports activity, allowing study of the application-specific characteristics of the dry electrodes, based on Ti-Me intermetallic thin films, and evaluation of the impact of the electrode-skin impedance on biopotential sensing. The electrode-skin impedance results support the reusability and the high degree of reliability of the Ti-Me dry electrodes. The Ti-Al films revealed the least performance as biopotential electrodes, while the Ti-Au system provided excellent results very close to the Ag/AgCl reference electrodes.
https://doi.org/10.3390/s21238143
Big Data Analytics APIs architecture for formative assessors. - In: 2021 IEEE Frontiers in Education Conference (FIE), (2021), insges. 9 S.
This Research to Practice Full Paper is driven by the question: Within limited time resources available to trainers in projects for Big Data Analytics (BDA) problems, how can they define project requirements for Formative Assessment (FA) actions? The paper suggests BDA APIs architecture as helping tool for formative assessors. It helps them effectively produce and adapt visual diagnostic reports for FA-actions in agile based requirements (i.e. features) definition. The paper presents two core architectures: Architecture for a parametrized feature-descriptor-system to define/refine a BDA API feature and its visual diagnostic reports, and an initial resources architecture for BDA API to initialize an analytics algorithm with its input big data sets. Clarifying visually the trainee's challenges (i.e. incremental features in a BDA API) is our main FA action. The FA action is designed based on Csikszentmihalyi's flow model to support a trainee in matching balance between his/her challenges and his/her skills. To test the architecture's functions, the paper has test setups for two formal projects (each has 1 to 6 trainees) and two informal projects (each has 1 to 3 trainees). The projects are to attack BDA problems in learning analytics and in image automatic classification. The test results show that the visual diagnostic reports produced by the trainers are very effective in clarifying visually incremental BDA API features not only for simple classifiers (i.e. classical data mining algorithms) but also for complex classifiers (i.e. deep learning algorithms). The results show also how visual diagnostic reports are easily produced for comparing the algorithm performances using different input big data sets, whereas other reports are produced for comparing performances between different algorithms, using one input data set. Related works are also discussed to show the architecture's differences and advantages. Its main advantages are: 1) it enables the trainers to use deep learning algorithms beside classical data mining algorithms in its BDA API parameterizable feature descriptors for visual diagnostic reports. 2) The descriptors can be extended, reused, shared, and scaled out to help trainers in other universities providing flow model based FA actions. 3) Finally, it has extensions to integrate other theoretical frameworks like Buckingham Shum and Deakin Crick's framework for dispositional learning analytics instead of the used flow model.
https://doi.org/10.1109/FIE49875.2021.9637431
Fractional-order parameter update law for adaptive control of integer-order systems. - In: The 2021 9th International Conference on Systems and Control (ICSC'21), (2021), S. 325-331
This contribution investigates the extension of the certainty equivalence based model reference adaptive control (MRAC) towards fractional-order parameter update laws. We use the infinite state representation of the fractional-order integral for constructing an integer-order Lyapunov function to derive the parameter update law. This renders the model reference error asymptotically stable.In comparison to the integer-order MRAC the fractional-order approach increases the robustness with respect to unstructured uncertainties and allows for higher adaptation rates due to the algebraic type of convergence. All the results are illustrated with a simulation example stabilizing the benchmark of the wing-rock dynamics.
https://doi.org/10.1109/ICSC50472.2021.9666578
Passivity-based control for the cart-pole in implicit port-Hamiltonian representation: an experimental validation. - In: 2021 European Control Conference (ECC), (2021), S. 2080-2085
This paper presents the design, analysis and experimental validation of a passivity-based control strategy for the local stabilization and swing-up of the well-known cart-pole system in implicit port-Hamiltonian representation. The stabilizing controller features the Interconnection and Damping Assignment Passivity-Based Control (IDA-PBC) method with an optimal local assignment. The swing-up controller is derived from the so-called energy-based control approach and underlines the stabilization of a level-set (homoclinic orbit). The combination of these controllers guarantees the swing-up and asymptotic stabilization of the upright pendulum position, as well as the desired cart location. The effectiveness of the proposed control scheme is verified via real-time experiments, and the results are compared with those from other authors.
https://doi.org/10.23919/ECC54610.2021.9655210
Observability analysis for spacecraft attitude determination using a single temperature sensor. - In: 2021 European Control Conference (ECC), (2021), S. 1438-1445
We consider the problem of spacecraft attitude determination using temperature data. Common algorithms fuse multiple temperature measurements to reconstruct the attitude. However, a single sensor already contains a lot of information due to the temperature dynamics inherent to the nonlinear structure. In this work a rigorous observability analysis is carried out to determine the configurations in which the combination of a single temperature sensor with angular velocity measurements is sufficient for estimating the entire attitude. We evaluate the observability properties of the different configurations and give recommendations for the best configurations.
https://doi.org/10.23919/ECC54610.2021.9654904
On the control design for the stabilisation of switched linear systems via eigenstructure assignment. - In: 2021 European Control Conference (ECC), (2021), S. 293-299
We are considering the control design problem for switched linear systems. We propose a method for the design of state-feedback controllers for the individual subsystems such that the closed-loop systems share a common eigenstructure. If additionally the eigenvalues of each individual subsystem can be chosen stable then the resulting switched system is stable for arbitrary switching. We present a necessary and a sufficient condition for which such controllers exist for systems of arbitrary order. For third-order systems, we show that a common eigenstructure can always be obtained by state-feedback given that the number of inputs offer enough degrees of freedom. We present a constructive procedure to obtain feedback controls such that the closed-loop systems have common eigenstructures. In all but one degenerated case the eigenvalues can be chosen arbitrarily such that the resulting closed-loop switched system is rendered asymptotically stable for arbitrary switching. We present an example for the degenerated case, where the eigenstructure may only be rectified if one of the closed-loop systems has a positive eigenvalue.
https://doi.org/10.23919/ECC54610.2021.9655006