University of Siegen
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Publication Access status: Metadata only , PATTERN RECOGNITION OF ROUGH SURFACES BY USING GONIOMETRIC SCATTERED LIGHT(2018); Nowadays, most techniques for evaluating rough metal surfaces are based on tactile or confocal measurement procedures.However, these technologies have disadvantages in respect to measuring speeds, resistance to vibration, impact and dust.In this paper we present a novel surface measurement approach, which uses the scattering light technology.Our approach enhances the state-of-the-art scattering light-based surface measurement methodology in both the detector setup and evaluation of the raw intensity values acquired by the scattered light device.The main goal in optimizing the measurement setup is to capture scattering parameters for rough surfaces in a range greater than 10 µm based on an enlarged detector array.Regarding the evaluation, we propose a pattern recognition approach which maps the reflection intensity I back to material structures and the tenpoint mean roughness Rz, the golden standard in tactile roughness characterization.Based on this approach, we are able to classify rough surface deviations like stripes using a simple but robust thresholding.In order to demonstrate the generality of our approach, we evaluate our approach using two rather different materials, i.e. brushed stainless steel and anodized aluminium.Source Type:ArticleDOI:10.24425/1181602 - Some of the metrics are blocked by yourconsent settings
Publication Access status: Metadata only , Performance improvements in horizontally integrated production networks through real-time reschedulingin the event of disruptionsRescheduling is a frequently used reactive strategy in order to limit the effects of disruptions on throughput times in multi-stage production processes. However, organizational deficits often cause delays in the information on disruptions, so rescheduling cannot limit disruption effects on throughput times optimally. Our approach strives for an investigation of possible performance improvements in multi-stage production processes enabled by realtime rescheduling in the event of disruptions. We developed a methodology whereby we could measure these possible performance improvements. For this purpose, we created and implemented a simulation model of a multi-stage production process. We defined system parameters and varied factors according to our experiment design, such as information delay, lot sizes and disruption durations. The simulation results were plotted and evaluated using DoE methodology. Dependent on the factor settings, we were able to prove large improvements by real-time rescheduling regarding the absorption of disruption effects in our experiments.Source Type:Article3 - Some of the metrics are blocked by yourconsent settings
Publication Access status: Open Access , Influence of phenylethylammonium iodide as additive in the formamidinium tin iodide perovskite on interfacial characteristics and charge carrier dynamicsA combined electrical and time-resolved optical investigation of the perovskite formamidinium tin iodide (FASnI3) and its phenylethylammonium (PEA) derivative PEA0.08FA0.92SnI3, which recently achieved a power conversion efficiency of 9%, is presented to study the specifics of contact characteristics and charge carrier dynamics. Microstructured gold electrode arrays were used to investigate the charge transport across a metal-perovskite interface and through micrometers of the perovskite films. Symmetrical contact configuration enabled detailed polarization studies. Hysteresis in the current-voltage characteristics and a corresponding current-time behavior indicated limitations by charge transfer in the contacts. Hysteresis was less pronounced in PEA0.08FA0.92SnI3 compared with FASnI3. This is explained by a 2-dimensional interlayer at the contacts, which leads to decreased field-induced migration of ions at the contact. Carrier recombination in the bulk of FASnI3 films, however, was only slightly modified by the presence of PEA. Femtosecond broadband transient absorption experiments up to 1.5 ns provided rate constants for the Auger and bimolecular recombination processes in FASnI3 of k3 = 1 × 10−29 cm6 s−1 and k2 = 3.1 × 10−10 cm3 s−1, respectively. In PEA0.08FA0.92SnI3, no significant differences in k2 and an only slightly increased k3 = 2 × 10−29 cm6 s−1 were measured. In extension to previous photoluminescence studies, we found efficient cooling of hot carriers by coupling to optical phonons (τcop = 0.5 ps), which is even faster than in lead perovskites. The authors thank the Deutsche Forschungsgemeinschaft (DFG) for financial support (Nos. SCHL 340/21-3, OU 58/10-3, LE 926/11-3, and RTG 2204). We are also grateful to R. Kentsch for complementary steady-state absorption and PL measurements, M. Morgenroth for assistance during the transient absorption experiments, H. Hemmelmann for measuring XRD at grazing incidence, and ZfM/LaMa (JLU Gieβen) for support in SEM and photolithography.Source Type:Article4 11 - Some of the metrics are blocked by yourconsent settings
Publication Access status: Open Access , Being accommodated, well then? ‘Scalar narratives’ on urban transformation and asylum seekers’ integration in mid-sized cities(2018)This article deals with the interplay between the rescaling processes of cities and pathways of asylum seekers’ integration. Building on scale theory and employing a downscaled mid-sized city in the Netherlands as a unit of analysis, two research questions are answered. Firstly, what kind of urban planning strategies do urban authorities of downscaled, midsized cities develop to rescale their cities? Secondly, how are these strategies related to the imagined pathways of asylum seeker integration? Here, the term ‘scale’ does not refer to an absolute ‘spatial object’ that is able to affect social reality. Rather, scales are socially produced through negotiation processes which are contested and heterogeneous. It is argued that Dutch urban authorities and housing corporations take a normative view of ‘pathways of integration’ and standardise these in terms of space, time and financing. By these socially produced scale processes, asylum seekers’ accommodation is well-managed, keeping the residents regulated and ‘in place’. Urban authorities utilise ‘scalar narratives’ to legitimate their interactions with asylum seekers and the way in which disadvantaged neighbourhoods in mid-sized cities are transformed. Using the Dutch mid-sized city Kerkrade as the case study, it is illustrated that local opportunity structures for integration are confined by (1) urban planning strategies mainly based on residential and tourism economies, (2) the perception of successful integration via a small-scale social mix within neighbourhoods, and (3) the neglect of public representation of cultural diversity.Source Type:Article6 10 - Some of the metrics are blocked by yourconsent settings
Publication Access status: Open Access , Relationship of sensation seeking with the neural correlates of appetitive conditioningPrevious research has linked sensation seeking with a heightened risk for drug abuse and other risk-taking behavior. As appetitive conditioning presents a model for the etiology and maintenance of addictive behavior, investigating sensation seeking in a classical conditioning paradigm might elucidate possible pathways toward addiction within this model. Furthermore, the theoretical concept underlying sensation seeking proposes a negative relationship between reward processing and sensation seeking in only moderately arousing situations, which has been neglected by previous research. This study aimed to investigate this inverse relationship in moderately stimulating situations entailing reward processing using functional magnetic resonance imaging. Subjects (N = 38) participated in a classical conditioning paradigm in which a neutral stimulus (CS+) was repeatedly paired with a monetary reward, while another neutral stimulus (CS−) was not. Imaging results revealed a negative relationship between sensation seeking and neural responses in the insula, amygdala and nucleus accumbens during the early phase and in the dorsal anterior cingulate cortex during the late phase of conditioning. These findings suggest reduced reward learning and consequently diminished processing of outcome expectancy in appetitive conditioning in subjects with high sensation seeking scores. The results are discussed with respect to clinical implications.Source Type:Article8 11 - Some of the metrics are blocked by yourconsent settings
Publication Access status: Open Access , Retraining automatic action tendencies for smoking using mobile phone-based approach-avoidance bias training: a study protocol for a randomized controlled studyBackground Automatic tendencies to approach drug-related cues have been linked to the development and maintainance of harmful drug-taking behavior. Recent studies have demonstrated that these automatic approach tendencies can be targeted directly by means of cognitive bias modification (CBM). Moreover, changing those approach tendencies may enhance treatment outcomes. However, training and therapy effects tend to be rather small and adherence to the training might be impaired by time-consuming multiple laboratory training sessions. Here, we present a protocol for a randomized controlled design to improve CBM training efficiency and facilitate access to the training by providing mobile-phone-based training sessions at home to current smokers motivated to quit smoking. Methods Participants (n = 100) are current smokers who smoke at least six cigarettes per day for at least 6 months and are willing to quit smoking. All participants attend a brief behavioral smoking cessation intervention (TAU) and are randomly assigned either to an experimental (TAU + training) or a control group. Participants in the experimental condition are given access to a training application (app) aimed at retraining automatic approach biases for smoking cues. Participants are instructed to perform the app training outside the laboratory context on a daily basis for 14 consecutive days. Participants in the control group do not receive the training. Primary outcome measures are changes in smoking-related approach biases and reductions in daily nicotine consumption as assessed at baseline, post-training and at 6-week follow up. Secondary outcome measures include approach biases for alternative stimuli or smoking stimuli to which participants were not exposed during training, attentional and association biases, biochemical outcomes, and self-reported smoking behavior, also measured at three different time points (baseline, post-training, and follow up). After completion of the study, smokers in the control condition will receive access to the training app. Discussion This randomized controlled trial is the first to test the effectiveness of an app-based CBM intervention as an adjunct to a brief smoking cessation intervention in smokers motivated to quit smoking. The results of this study can inform future research in the optimization and advancement of CBM treatment for addiction.Source Type:Article3 12 - Some of the metrics are blocked by yourconsent settings
Publication Access status: Open Access , Gender differences in blood transfusion strategy for patients with hip fractures - a retrospective analysisBackground: In the last decades, transfusion therapy with allogenic blood has progressively shifted to a more restrictive approach. The current study analyzed the transfusion practice and transfusion-associated factors in a regional trauma center over the course of five years. Methods: Retrospective analysis of all patients undergoing surgery for hip fractures in a level 1 trauma center of an academic teaching hospital from 2010 to 2014 (n=650). The number of transfused packed red blood cells (PRBCs), preoperative Hb concentrations, and intensive care unit (ICU) and hospital length of stay (LOS) were analyzed. A logistic regression analysis was performed to evaluate transfusion and ICU LOS-associated risk factors. (Ethical Review Board approval: 2015-497-f-S). Results: From 2010 to 2014 the average number of PRBCs transfused per patient decreased continuously despite similar preoperative Hb levels. During the same period, ICU LOS increased while hospital LOS decreased. Advanced patient age, preoperative Hb concentrations, surgical complications, and ICU LOS were associated with increased transfusion requirements. Although preoperative Hb levels were lower, females received fewer PRBCs compared to males. Conclusion: Over the course of five years, a restrictive transfusion strategy was implemented within clinical practice in patients undergoing surgery for hip fractures. In parallel, a significant reduction in the hospital LOS and an increased ICU LOS was noted. Whether there is an association between increased ICU LOS and decreasing hospital LOS and whether there is a gender effect on transfusion requirements in patients with surgery for hip fractures should be subject to further research.Source Type:Article1 6 - Some of the metrics are blocked by yourconsent settings
Publication Access status: Open Access , Performance optimization of a Kirsten–Boeing turbine by a metamodel based on neural networks coupled with CFDThe supply of energy is sustainable only if it is predominantly based on renewable or regenerative energies. For this reason, the use of micro-hydropower plants on rivers and streams is considered recently. This is a particular challenge for the preservation of ecologically permeable streams, so that no dams or similar structures can be considered. While the axial turbine design has prevailed in wind power, there is still no consensus for the generation of energy in free water flow conditions. In this work, an existing prototype of an unusual vertical axis Kirsten–Boeing turbine was investigated. A multivariate optimization process was created, in which all important machine parameters were checked and improved. By using neural networks as a metamodel coupled with flow simulations in ANSYS CFX, a broadly applicable optimization strategy is presented that yielded a blade design that is 36% more efficient than its predecessor in experiments. During the process, it was shown how to set up a complex sliding mesh problem with ANSYS expressions while evaluating a free surface problem.Source Type:Article3 8 - Some of the metrics are blocked by yourconsent settings
Publication Access status: Open Access , Data on the current state of problem solving and improvement during physical product development within complex (manufacturing) systems(2019); ; Due to the exponential increase of failure cost during the product development process, problems have to be effectively remedied as early as possible and with shortened innovation cycles, increasingly efficient. For the manufacturing of complex products at low maturity levels (referred to as physical product development), nonconformance problem solving constitutes a major difficulty in this regard (Camarillo et al., 2017; Walter et al., 2010). The data presented in this article was collected from German companies, differing in size and industry sector, manufacturing highly complex products at low maturity. Selected and consulted companies therefore operate in (or comparable to) the automotive prototyping, air and space, shipbuilding, special machinery or electronics domain. The survey comprises the answers of 46 participants, gathered via online questionnaire. It subdivides into 18 questions covering the companies’ characteristics, knowledge management and documentation systems within the product development process, as well as the appraisal of technological potentials. The obtained data gives an insight into the industrial status quo of nonconformance problem solving. The data allows to derive existing deficits and dedicated research on solutions.Source Type:Article1 24 - Some of the metrics are blocked by yourconsent settings
Publication Access status: Open Access , Zebrafish larvae show negative phototaxis to near-infrared lightZebrafish larvae (Danio rerio) are among the most used model species to test biological effects of different substances in biomedical research, neuroscience and ecotoxicology. Most tests are based on changes in swimming activity of zebrafish larvae by using commercially available high-throughput screening systems. These systems record and analyse behaviour patterns using visible (VIS) and near-infrared (NIR) light sources, to simulate day (VIS) and night (NIR) phases, which allow continuous recording of the behaviour using a NIR sensitive camera. So far, however, the sensitivity of zebrafish larvae to NIR has never been tested experimentally, although being a critical piece of information for interpreting their behaviour under experimental conditions. Here, we investigated the swimming activity of 96 hpf (hours post fertilization) and 120 hpf zebrafish larvae under light sources of NIR at 860 nm and at 960 nm wavelength and under VIS light. A thermal source was simultaneously presented opposite to one of the light sources as control. We found that zebrafish larvae of both larval stages showed a clear negative phototactic response towards 860 nm NIR light and to VIS light, but not to 960 nm NIR light. Our results demonstrated that zebrafish larvae are able to perceive NIR at 860 nm, which is almost identical to the most commonly used light source in commercial screening systems (NIR at 850 nm) to create a dark environment. These tests, however, are not performed in the dark from the zebrafish´s point of view. We recommend testing sensitivity of the used test organism before assuming no interaction with the applied light source of commonly used biosensor test systems. Previous studies on biological effects of substances to zebrafish larvae should be interpreted with caution.Source Type:Article5 10
