Impact of seasonal weather on forecasting of power quality disturbances in distribution grids

Power supply disruptions, including short-time disturbances, can lead to large direct and indirect financial losses. The ability to predict the risk of these disturbances allows for preventive actions and increases the reliability of the supply. This paper investigates the impact of using seasonal data of combined common weather conditions on the power quality prediction in distribution grids. Our main contribution consists of weatherbased predictive models for three types of events that frequently occur in these grids, as well as an analysis of the influence of two training approaches: with either seasonal or all-year data, on their performance. All developed models score higher than arbitrary guessing; in several instances the improvement is considerable. It is demonstrated that in some cases the models improve when the training data is limited to a subset corresponding to a particular meteorological season. Examining variable importance values and distributions of the models’ data, it is shown that this situation takes place particularly when weather conditions correlated with the occurrence of power grid events vary across seasonsacceptedVersio

Retrospektive Analyse unterschiedlicher operativer Behandlungsmethoden der distalen Radiusfrakturen beim Erwachsenen unter Verwendung subjektiver Fragebögen

Ziel dieser retrospektiven Studie eines definierten Patientenkollektivs war der Ergebnisvergleich zwischen der Kirschner-Drahtosteosynthese, dem Fixateur externe und der winkelstabilen volaren Platte bei distalen Radiusfrakturen Erwachsener in Bezug auf deren subjektive Zufriedenheit und Gesundheitswahrnehmung. Hierzu sollten SF-36 Health Survey und DASH-Score angewandt werden. Zudem sollte geprüft werden, ob diese Messmethoden als praktikable und valide Instrumente für die Kontrolle von Ergebnissen in der Therapie der distalen Radiusfraktur eingesetzt werden können und im Qualitätsmanagement Verwendung finden

The IkB–NF-kB Signaling Module: Temporal Control and Selective Gene Activation

Nuclear localization of the transcriptional activator NF-κB (nuclear factor κB) is controlled in mammalian cells by three isoforms of NF-κB inhibitor protein: IκBα, -β, and -ɛ. Based on simplifying reductions of the IκB–NF-κB signaling module in knockout cell lines, we present a computational model that describes the temporal control of NF-κB activation by the coordinated degradation and synthesis of IκB proteins. The model demonstrates that IκBα is responsible for strong negative feedback that allows for a fast turn-off of the NF-κB response, whereas IκBβ and -ɛ function to reduce the system's oscillatory potential and stabilize NF-κB responses during longer stimulations. Bimodal signal-processing characteristics with respect to stimulus duration are revealed by the model and are shown to generate specificity in gene expression

Lessons for Data-Driven Modelling from Harmonics in the Norwegian Grid

With the advancing integration of fluctuating renewables, a more dynamic demand-side, and a grid running closer to its operational limits, future power system operators require new tools to anticipate unwanted events. Advances in machine learning and availability of data suggest great potential in using data-driven approaches, but these will only ever be as good as the data they are based on. To lay the ground-work for future data-driven modelling, we establish a baseline state by analysing the statistical distribution of voltage measurements from three sites in the Norwegian power grid (22, 66, and 300 kV). Measurements span four years, are line and phase voltages, are cycle-by-cycle, and include all (even and odd) harmonics up to the 96 order. They are based on four years of historical data from three Elspec Power Quality Analyzers (corresponding to one trillion samples), which we have extracted, processed, and analyzed. We find that: (i) the distribution of harmonics depends on phase and voltage level; (ii) there is little power beyond the 13 harmonic; (iii) there is temporal clumping of extreme values; and (iv) there is seasonality on different time-scales. For machine learning based modelling these findings suggest that: (i) models should be trained in two steps (first with data from all sites, then adapted to site-level); (ii) including harmonics beyond the 13 is unlikely to increase model performance, and that modelling should include features that (iii) encode the state of the grid, as well as (iv) seasonality. View Full-Text Keywords: machine learning; power systems; harmonic distortion; power qualitypublishedVersio

Modified minimally invasive extensor carpi radialis longus tenodesis for scapholunate dissociation:A prospective observational study

Background: Scapholunate dissociation is the most common form of carpal instability. However, there is no gold standard for operative treatment. In this prospective observational study on 54 patients, a modified minimally invasive dynamic extensor carpi radialis longus tenodesis is described, which is characterized by a smaller approach and application of a cannulated screw and washer for tendon fixation.Methods: Quick-Disabilities of Arm, Shoulder and Hand (DASH)-questionnaire results, post-operative satisfaction, range of motion and grip strength are analyzed.Results: A median Quick-DASH of 54.6 was observed pre-operatively which significantly improved to a median of 28.4 after the procedure (p &lt;0.001). Median follow-up was 24 months. Of 46 completely followed-up patients, 31 patients (67.4%) reported that they were satisfied with the outcome. Thirty-seven patients (80.4%) would recommend the procedure to a friend. Thirty-five patients (76.1%) reported some kind of complaint in the operated hand during follow-up. There was no association of severity of symptoms and co-morbidities with the outcome. Neither palmar flexion, nor dorsal extension was significantly different between the operated and non-operated wrist. The operated wrists were observed to have less grip strength than non-operated wrists.Conclusions: The presented method seems to be as successful as other techniques described in literature. It is less invasive, thus more patient friendly without harming feasibility of future salvage options. However, post-operative complaint rate was quite high.</p

Understanding NF-κB signaling via mathematical modeling

Mammalian inflammatory signaling, for which NF-κB is a principal transcription factor, is an exquisite example of how cellular signaling pathways can be regulated to produce different yet specific responses to different inflammatory insults. Mathematical models, tightly linked to experiment, have been instrumental in unraveling the forms of regulation in NF-κB signaling and their underlying molecular mechanisms. Our initial model of the IκB–NF-κB signaling module highlighted the role of negative feedback in the control of NF-κB temporal dynamics and gene expression. Subsequent studies sparked by this work have helped to characterize additional feedback loops, the input–output behavior of the module, crosstalk between multiple NF-κB-activating pathways, and NF-κB oscillations. We anticipate that computational techniques will enable further progress in the NF-κB field, and the signal transduction field in general, and we discuss potential upcoming developments