Integration erneuerbarer Energiequellen in das Schweizer Verteilnetz: Möglichkeiten von Microgrids

Die Literaturstudie wurde von den Elektrizitätswerken des Kantons Zürich (EKZ) im Rahmen ihrer Hochschulförderung finanziell unterstützt.Microgrids sind eine vielversprechende Möglichkeit, die zunehmende Anzahl EE-Anlagen verhältnismässig kostengünstig in das bestehende Stromnetz zu integrieren. Viele technische Komponenten befinden sich jedoch noch in der Entwicklungsphase und werden erst in der Zukunft wirtschaftlich einsetzbar sein. Trotzdem werden derzeit schon verschiedene grosse Microgrids in Pilotprojekten weltweit implementiert. Offiziell und langfristig ins Netz integriert wurden bisher meist nur kleine Microgrids, typischerweise zur rudimentären Stromversorgung oder auf Gebäude- oder Campus-Ebene. Die Rolle der Verteilnetzbetreiber wird sich mit der Einführung von Microgrids erheblich ändern und erweitern, da sie damit aktiver in das Stromgeschehen eingreifen können. In der Schweiz werden die gesetzlichen Rahmenbedingungen für die Einbindung von Microgrids momentan erst noch ausgearbeitet, welche die möglichen Implementierungen von Microgrids, beispielsweise über Vergütungsanreize, in den nächsten Jahren stark beeinflussen können

Hoher Stromertrag von Schweizer PV-Anlagen auch mit Leistungsbegrenzung

Eine Begrenzung der Einspeiseleistung von PV-Anlagen ist in manchen Ländern bereits Pflicht, um das Netz an schönen Tagen mit hoher Einstrahlung nicht zu überlasten. Dabei wird meist eine Abregelung auf 70% der Nennleistung umgesetzt. Was würde diese Massnahme für Anlagenbetreiber in der Schweiz genau bedeuten? Im Schweizer Mittelland könnte die Begrenzung der Einspeiseleistung entweder fix auf 70% der installierten Modulleistung oder (besser) flexibel unter Berücksichtigung des Eigenverbrauches durchaus sinnvoll sein. Bei PV-Anlagen im Gebirge sollte im Einzelfalle geprüft werden, ob eine allfällige Abregelung von Produktionsspitzen durch Eigenverbrauch oder z.B. durch den Einsatz von Akkus verhindert werden soll. Auch eine regional unterschiedliche Leistungsbegrenzung auf 80% oder 90% in Gebieten mit sehr hoher solarer Einstrahlung wäre denkbar

Respiratory and cardiac monitoring at night using a wrist wearable optical system

Sleep monitoring provides valuable insights into the general health of an individual and helps in the diagnostic of sleep-derived illnesses. Polysomnography, is considered the gold standard for such task. However, it is very unwieldy and therefore not suitable for long-term analysis. Here, we present a non-intrusive wearable system that, by using photoplethysmography, it can estimate beat-to-beat intervals, pulse rate, and breathing rate reliably during the night. The performance of the proposed approach was evaluated empirically in the Department of Psychology at the University of Fribourg. Each participant was wearing two smart-bracelets from Ava as well as a complete polysomnographic setup as reference. The resulting mean absolute errors are 17.4 ms (MAPE 1.8%) for the beat-to-beat intervals, 0.13 beats-per-minute (MAPE 0.20%) for the pulse rate, and 0.9 breaths-per-minute (MAPE 6.7%) for the breath rate.Comment: Submitted to the 40th International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC

PLoS One

Age-related macular degeneration (AMD) is a common, progressive multifactorial vision-threatening disease and many genetic and environmental risk factors have been identified. The risk of AMD is influenced by lifestyle and diet, which may be reflected by an altered metabolic profile. Therefore, measurements of metabolites could identify biomarkers for AMD, and could aid in identifying high-risk individuals. Hypothesis-free technologies such as metabolomics have a great potential to uncover biomarkers or pathways that contribute to disease pathophysiology. To date, only a limited number of metabolomic studies have been performed in AMD. Here, we aim to contribute to the discovery of novel biomarkers and metabolic pathways for AMD using a targeted metabolomics approach of 188 metabolites. This study focuses on non-advanced AMD, since there is a need for biomarkers for the early stages of disease before severe visual loss has occurred. Targeted metabolomics was performed in 72 patients with early or intermediate AMD and 72 control individuals, and metabolites predictive for AMD were identified by a sparse partial least squares discriminant analysis. In our cohort, we identified four metabolite variables that were most predictive for early and intermediate stages of AMD. Increased glutamine and phosphatidylcholine diacyl C28:1 levels were detected in non-advanced AMD cases compared to controls, while the rate of glutaminolysis and the glutamine to glutamate ratio were reduced in non-advanced AMD. The association of glutamine with non-advanced AMD corroborates a recent report demonstrating an elevated glutamine level in early AMD using a different metabolomics technique. In conclusion, this study indicates that metabolomics is a suitable method for the discovery of biomarker candidates for AMD. In the future, larger metabolomics studies could add to the discovery of novel biomarkers in yet unknown AMD pathways and expand our insights in AMD pathophysiology

Microgrids : Chancen und Herausforderungen für Verteilnetzbetreiber

Eine zuverlässige Stromversorgung gewinnt an Bedeutung, da sich immer grössere Teile der Wirtschaft und des Lebens digital abspielen. Dabei geht es längst nicht nur darum, dass Smartphone-Nutzer irritiert sind, wenn sie bei Stromausfall ihr Gerät nicht mehr aufladen können. Fabriken können ohne Strom nicht produzieren und Lebensmittel verderben in Kühlhäusern. Auch wenn die Stromsicherheit in der Schweiz im internationalen Vergleich sehr hoch ist, sind Stromausfälle möglich, und das mit immer schwerwiegenderen Folgen. Microgrids könnten in diesem Kontext einen wertvollen Beitrag leisten

The contribution of water surface Fresnel reflection to BIPV yield

Fresnel reflection on a water surface is highly variable throughout the year and can have a significant influence on building-integrated vertical PV panels, yet is generally disregarded in yield calculations. We analyze beam irradiances of two horizontal pyranometers situated next to a lake, one facing upwards and one facing downwards, to estimate the contribution of Fresnel reflection to the beam irradiance on a vertical surface. We show that in general the observed beam irradiance on the downward facing instrument matches the calculated Fresnel reflection. In contrast to other studies investigating water albedo, we also found that the reflection percentage decreases consistently with higher wind speeds and lower solar zenith angle. Fresnel reflection has the highest contribution for vertical surfaces in winter, with varying contributions between 30% of monthly global irradiance over the course of one year for different latitudes, and should thus be included in yield estimates for building integrated PV installations situated next to bodies of water

Wearable Sensors Reveal Menses-Driven Changes in Physiology and Enable Prediction of the Fertile Window: Observational Study

Background: Previous research examining physiological changes across the menstrual cycle has considered biological responses to shifting hormones in isolation. Clinical studies, for example, have shown that women’s nightly basal body temperature increases from 0.28 to 0.56 ˚C following postovulation progesterone production. Women’s resting pulse rate, respiratory rate, and heart rate variability (HRV) are similarly elevated in the luteal phase, whereas skin perfusion decreases significantly following the fertile window’s closing. Past research probed only 1 or 2 of these physiological features in a given study, requiring participants to come to a laboratory or hospital clinic multiple times throughout their cycle. Although initially designed for recreational purposes, wearable technology could enable more ambulatory studies of physiological changes across the menstrual cycle. Early research suggests that wearables can detect phase-based shifts in pulse rate and wrist skin temperature (WST). To date, previous work has studied these features separately, with the ability of wearables to accurately pinpoint the fertile window using multiple physiological parameters simultaneously yet unknown. Objective: In this study, we probed what phase-based differences a wearable bracelet could detect in users’ WST, heart rate, HRV, respiratory rate, and skin perfusion. Drawing on insight from artificial intelligence and machine learning, we then sought to develop an algorithm that could identify the fertile window in real time. Methods: We conducted a prospective longitudinal study, recruiting 237 conception-seeking Swiss women. Participants wore the Ava bracelet (Ava AG) nightly while sleeping for up to a year or until they became pregnant. In addition to syncing the device to the corresponding smartphone app daily, women also completed an electronic diary about their activities in the past 24 hours. Finally, women took a urinary luteinizing hormone test at several points in a given cycle to determine the close of the fertile window. We assessed phase-based changes in physiological parameters using cross-classified mixed-effects models with random intercepts and random slopes. We then trained a machine learning algorithm to recognize the fertile window. Results: We have demonstrated that wearable technology can detect significant, concurrent phase-based shifts in WST, heart rate, and respiratory rate (all P<.001). HRV and skin perfusion similarly varied across the menstrual cycle (all P<.05), although these effects only trended toward significance following a Bonferroni correction to maintain a family-wise alpha level. Our findings were robust to daily, individual, and cycle-level covariates. Furthermore, we developed a machine learning algorithm that can detect the fertile window with 90% accuracy (95% CI 0.89 to 0.92). Conclusions: Our contributions highlight the impact of artificial intelligence and machine learning’s integration into health care. By monitoring numerous physiological parameters simultaneously, wearable technology uniquely improves upon retrospective methods for fertility awareness and enables the first real-time predictive model of ovulation

Vision and touch are automatically integrated for the perception of sequences of events

Bresciani J-P, Dammeier F, Ernst MO. Vision and touch are automatically integrated for the perception of sequences of events. Journal of Vision. 2006;6(5):2.The purpose of the present experiment was to investigate the integration of sequences of visual and tactile events. Subjects were presented with sequences of visual. ashes and tactile taps simultaneously and instructed to count either the. ashes ( Session 1) or the taps ( Session 2). The number of. ashes could differ from the number of taps by +/-1. For both sessions, the perceived number of events was significantly influenced by the number of events presented in the task-irrelevant modality. Touch had a stronger influence on vision than vision on touch. Interestingly, touch was the more reliable of the two modalities-less variable estimates when presented alone. For both sessions, the perceptual estimates were less variable when stimuli were presented in both modalities than when the task-relevant modality was presented alone. These results indicate that even when one signal is explicitly task irrelevant, sensory information tends to be automatically integrated across modalities. They also suggest that the relative weight of each sensory channel in the integration process depends on its relative reliability. The results are described using a Bayesian probabilistic model for multimodal integration that accounts for the coupling between the sensory estimates