Fachhochschule Bielefeld
  • Bielefeld, Germany
Recent publications
Objective It has been shown that variable compared to fixed task prioritization during dual task practice more effectively improves motor (i.e., postural control) and cognitive (i.e., memory) performance in older adults. However, it is unclear whether this finding is also valid in young adults. Thus, the present study examined the effect of fixed (allocate equal priority on both tasks) versus variable (vary priority between both tasks) priority during short-term motor-cognitive dual task practice on single and dual task performance in healthy young adults (age range: 20–30 years). Results During two days of practice, significant improvements of motor (i.e., balance task: reduced root mean square error; p < 001, η p ² = .72) and cognitive (i.e., arithmetic task: increased serial three subtractions; p < .001, η p ² = .78) task performance were observed and that was irrespective of group (“fixed priority” and “variable priority”). Further, the statistical analysis of post-practice single and dual task performance revealed no significant differences between groups, irrespective of task (i.e., motor or cognitive). This indicates that in young as opposed to old adults, single and dual task performance improvements are independent of task prioritization (i.e., fixed or variable priority) during short-term motor-cognitive dual task practice.
Three-dimensional printing enables building objects shaped with a large degree of freedom. Additional functionalities can be included by modifying the printing material, e.g., by embedding nanoparticles in the molten polymer feedstock, the resin, or the solution used for printing, respectively. Such composite materials may be stronger or more flexible, conductive, magnetic, etc. Here, we give an overview of magnetic composites, 3D-printed by different techniques, and their potential applications. The production of the feedstock is described as well as the influence of printing parameters on the magnetic and mechanical properties of such polymer/magnetic composites.
Background: Service user satisfaction in inpatient psychiatric care is often measured with instruments that have been designed by professionals, without involving the perspective of service users. Views on Inpatient Care (VOICE), developed in England, is among the first service-user-generated outcome measures which included service users’ perspectives in the process. Aims: In this study, we aimed to validate a German version of VOICE. Methods: The original questionnaire was translated into German and validated using data collected from 163 inpatients undergoing treatment in a psychiatric hospital. The instrument was tested for its psychometric properties, focusing on measurements of reliability and construct validity. Also, we assessed the impact of demographic variables. Finally, factorial analyses were carried out to compare the underlying factorial structure to the English version. Results: The analyses revealed a high internal consistency (α = 0.90). No significant impact of demographic variables was observed. Factorial analyses indicated a one-factor structure which accounted for 40.39% of variance. Conclusions: Psychometrical evaluation of VOICE-DE indicated the questionnaire to be a suitable tool to assess service users’ personal experience with treatment and satisfaction in German.
Currently, the accuracy of modeling a photovoltaic (PV) array for fault diagnosis is still unsatisfactory due to the fact that the modeling accuracy is limited by the accuracy of extracted model parameters. In this paper, the modeling of a PV array based on multi-agent deep reinforcement learning (RL) using the residuals of I–V characteristics is proposed. The environment state based on the high dimensional residuals of I–V characteristics and the corresponding cooperative reward is presented for the RL agents. The actions of each agent considering the damping amplitude are designed. Then, the entire framework of modeling a PV array based on multi-agent deep RL is presented. The feasibility and accuracy of the proposed method are verified by the one-year measured data of a PV array. The experimental results show that the higher modeling accuracy of the next time step is obtained by the extracted model parameters using the proposed method, compared with that using the conventional meta-heuristic algorithms and the analytical method. The daily root mean square error (RMSE) is approximately 0.5015 A on the first day, and converges to 0.1448 A on the last day of training. The proposed multi-agent deep RL framework simplifies the design of states and rewards for extracting model parameters.
Torsional vibration is an oscillation phenomenon occurring at driven railway vehicle wheelsets. As the resulting dynamic stresses can be significantly larger than the maximum static motor torque, axle and press fit are at risk of failure. To prevent dangerous vibration events and with these, press fit and axle from failure, traction drive manufactures nowadays used to implement vibration suppression algorithms in drive controls. In this paper, the effectiveness of such suppression algorithms is analyzed. Furthermore, as a pilot survey, we analyze to what extend traction controls influence the excitation of torsional vibration.
This new Special Issue of Materials entitled “3D/4D Printing Application for Shape Memory Materials” aims to publish original and review papers dealing with basic and applied research on this emerging technology [...]
Brown and Isaacs' World Café is a participatory research method to make connections to the ideas of others. During the SARS-CoV-2 pandemic and the corresponding contact restrictions, only digital hostings of World Cafés were possible. This article aims to present and reflect on the potentials and challenges of hosting online World Cafés and to derive recommendations for other researchers. Via Zoom and Conceptboard, three online World Cafés were conducted in August 2021. In the World Cafés, the main focus was on the increasing digitization in settings in the context of health promotion and prevention from the perspective of setting members of educational institutions , leisure clubs, and communities. Between 9 and 13 participants participated in three World Cafés. Hosting comprises the phases of design and preparation, realisation, and evaluation. Generally , hosting an online World Café is a suitable method for participatory engagement, but particular challenges have to be overcome. Overall café hosts must create an equal participation environment by ensuring the availability of digital devices and stable internet access. The event schedule must react flexibly to technical disruptions and varying participation numbers. Further, compensatory measures such as support in the form of technical training must be implemented before the event. Finally, due to the higher complexity of digitalisation, roles of participants and staff need to be distributed and coordinated.
In times of climate change and increasing resource scarcity, the importance of sustainable renewable energy technologies is increasing. However, the photovoltaic (PV) industry is characterised by linear economy structures, energy-intensive production, downcycling and little sustainability. One starting point for sustainable technologies is offered by the circular economy with its circular design principles. One problematic aspect of the design of crystalline PV modules is the encapsulation. In particular, the encapsulation avoids high-value recycling or the remanufacturing of modules, which could close loops and extend the lifetime of the products. For this reason, this paper provides an overview of the current state of encapsulation methods regarding production, materials and recycling. In addition, the current state of sustainability research in the photovoltaic sector is presented using the VOSviewer tool. Furthermore, alternative encapsulation technologies are discussed and compared in terms of performance and sustainability. The current encapsulation method using ethylene vinyl acetate as the encapsulation material offers major disadvantages in terms of performance and recyclability. Alternatives are the thermoplastic material polyolefin and the alternative structure of the NICE technology. Overall, however, research should focus more on sustainability and recyclability. Alternative module structures will be a decisive factor in this context.
Highlights Magnetic single droplet and four-droplet spheres systems were examined with respect to their energy landscapes For thin oxide layers, the numbers of extrema are similar to spheres without coating For an oxide coated system, the maximum packing density is increased by 12%, as compared to the non-coated system Improved magnetic memory systems belong to the main research topics in spintronics. Here we show micromagnetic simulations used to analyze the energy density of nano-scaled iron spheres. Layers of different thickness, partly coated with iron oxide, were tested in terms of spatial uniformity of the physical system energy. For a single non-coated or iron-oxide coated droplet, the spatial distribution of the total energy is not uniform and depends on the nano-droplet size. Additionally, for systems consisting of four objects, the relation between relative distance and the resultant magnetization distribution was analyzed. The mutual relation between droplet size and the underlying magnetization distribution as well as the character of local energy extrema was investigated. The size changes for the four-droplet system were compared with the single object behavior to obtain a criterion for the minimum distance between spheres to behave as a single object. The calculations revealed that the oxidized spheres could be placed closer to each other in comparison to the non-coated system. For the proposed oxide coated system, the increase of this maximum packing density is equal to about 12%, as compared to the non-coated system.
Polyaniline (PAni)–coated ZnO–SiO2–based hybrid material was prepared successfully with the in-situ polymerisation method and the product was subsequently analysed using XPS, XRD, TEM, UV-vis, TGA, FTIR and BET. The optical band gap calculated from the Tauc plot was found to be 2.89 eV. Moreover, this work reports an extensive study of the effect of the SiO2 on the electrochemical performance of hybrid material based on ZnO and PAni employing cyclic voltammetry. Furthermore, to evaluate the adsorption of methylene blue (MB), the parameters for the effectiveness of the adsorption process, including pH value, concentration and temperature, were investigated. The results indicated that the maximum adsorption of MB on the produced hybrid material occurred at pH 6.8 with a capacity reaching 71.2 mg.g⁻¹. The thermodynamic studies indicate that the adsorption of MB on this adsorbent is spontaneous and endothermic in nature. Furthermore, [email protected]–SiO2 is attractive for treating the effluents containing dyes due to its recyclability and high removal capacity.
Intelligent buildings offer a great opportunity to evacuate people more efficiently and safely by using dynamic evacuation guidance systems in comparison to static escape route signs. Static systems are unable to react to temporary events; their signs might guide the occupants directly to the hazard in the worst case. A dynamic system on the other hand determines the hazard position and calculates and displays an alternative escape route to avoiding the hazard position. In this work, we present a detailed study of current research approaches and introduce two algorithms developed for building evacuation. The first algorithm demonstrates the static evacuation and leads directly to the nearest exit. The second algorithm reacts dynamically to temporary events such as fire. A comparison of these algorithms shows that the dynamic system is more efficient. In order to test the dynamic approach in a real environment, a device to display the evacuation route is required. We propose a novel interactive evacuation approach using mixed reality glasses (HoloLens) for user guidance. A user study shows the advantages of the HoloLens and verifies our findings from the simulation in a real environment.
Data carriers using spin waves in spintronic and magnonic logic devices offer operation at low power consumption and free of Joule heating yet requiring noncollinear spin structures of small sizes. Heterometallic rings can provide such an opportunity due to the controlled spin-wave transmission within such a confined space. Here, we present a series of {ScnGdn} (n = 4, 6, 8) heterometallic rings, which are the first Sc-Ln clusters to date, with tunable magnetic interactions for spin-wave excitations. By means of time- and temperature-dependent spin dynamics simulations, we are able to predict distinct spin-wave excitations at finite temperatures for Sc4Gd4, Sc6Gd6, and Sc8Gd8. Such a new model is previously unexploited, especially due to the interplay of antiferromagnetic exchange, dipole-dipole interaction, and ring topology at low temperatures, rendering the importance of the latter to spin-wave excitations.
Magnetic nanoparticles can be embedded in electrospun nanofibers and other polymeric matrices to prepare magnetic composites with defined magnetic and mechanical properties. Metal-oxide nanoparticles, such as magnetite or nickel-ferrite, are of special interest since they do not need a coating to avoid oxidation. Like other nanoparticles, these metal-oxide nanoparticles tend to form agglomerations, in this way modifying the magnetic properties of the composites. After studying this effect for the magnetic elements Co, Fe, Ni as well as permalloy (Py) in a previous study, defining a new method to quantify the nanoparticle distribution in a polymer, here we concentrate on the influence of agglomerations on the magnetic properties of metal-oxide nanoparticles with different diameters in non-magnetic matrices.
Selbstbehandlungsansätze werden bereits seit längerer Zeit als Alternative zu bestehenden psychotherapeutischen und pharmakologischen Behandlungsansätzen diskutiert, u. a. im Rahmen von „Stepped-care-Modellen“ (Mitchell et al. 2011; Ramklint et al. 2012). Der überwiegende Teil basiert auf Therapiemanualen, die wesentliche Elemente der KVT-Ansätze enthalten. In der Therapieforschung wird, nicht zuletzt aus ökonomischen Gründen, in den letzten Jahren ein stufenweises Vorgehen in der Behandlung psychischer Störungen propagiert. Die erste Stufe stellen „niederschwellige“ Therapieansätze dar. In der Literatur werden hierfür Begriffe verwendet wie Selbsthilfe (SH), Selbstbehandlung, Selbstveränderung oder Bibliotherapie. In der revidierten S3-Leitlinie (AWMF 2018) wird von „Selbstmanagement“ im Gegensatz zu Selbsthilfe gesprochen, da es sich bei den in die Meta-Analysen eingegangenen Studien um Ansätze handelt, die auf strukturierten evaluierten Programmen basieren und sich damit von klassischen Selbsthilfegruppen unterscheiden. Es wurden Selbsthilfemanuale entwickelt, die den Richtlinien der kognitiv-verhaltenstherapeutischen Ansätze (KVT-Ansätze) folgen und mit minimaler therapeutischer Begleitung (angeleitet, ASH) oder ohne (rein, RSH) von den Betroffenen selbstständig durchgeführt werden können. Solche Selbstmanagementprogramme für Patientinnen mit Essstörungen stehen in Online- und Offline-Versionen zur Verfügung und reichen von reiner Selbsthilfe mithilfe eines Buches (Bibliotherapie), einer App oder einem Computerprogramm über Programme mit zeitweisem Therapeutenkontakt bis hin zu geleiteten Selbsthilfeprogrammen. Neben einem persönlichen Kontakt können diese Therapeutenkontakte in einem Audio- und Video-Chat-Programm oder aber schriftlich im Chat oder per E-Mail stattfinden, wobei das Letztere eine asynchrone Kommunikation erlaubt. Die unterstützenden Kurzkontakte nehmen weniger Zeit in Anspruch als Psychotherapiesitzungen, und deren Inhalt ist im engeren Sinne nicht psychotherapeutisch.
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1,523 members
Christian Grebe
  • Wirtschaft und Gesundheit
Gerrit Hirschfeld
  • Fachbereich Wirtschaft
Alaa Tharwat
  • Fachbereich Ingenieurwissenschaften und Mathematik
Kirsten Bergmann
  • Fachbereich Ingenieurwissenschaften und Mathematik
Interaktion 1, 33619, Bielefeld, Germany
Head of institution
Prof. Dr. Ingeborg Schramm-Wölk