384 research outputs found

    Demand response through decentralized optimization in residential areas with wind and photovoltaics

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    A paradigm shift has to be realized in future energy systems with high shares of renewable energy sources. The electrical demand has to react to the fluctuating electricity generation of renewable energy sources. To this end, flexible electrical loads like electric heating devices coupled with thermal storage or electric vehicles are necessary in combination with optimization approaches. In this paper, we develop a novel privacy-preserving approach for decentralized optimization to exploit load flexibility. This approach, which is based on a set of schedules, is referred to as SEPACO-IDA. The results show that our developed algorithm outperforms the other approaches for scheduling based decentralized optimization found in the literature. Furthermore, this paper clearly illustrates the suboptimal results for uncoordinated decentralized optimization and thus the strong need for coordination approaches. Another contribution of this paper is the development and evaluation of two methods for distributing a central wind power profile to the local optimization problem of distributed agents (Equal Distribution and Score-Rank-Proportional Distribution). These wind profile assignment methods are combined with different decentralized optimization approaches. The results reveal the dependency of the best wind profile assignment method on the used decentralized optimization approach

    Impact of different control strategies on the flexibility of power-to-heat-systems

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    High Active Material Loading in Organic Electrodes Enabled by an in‐situ Electropolymerized π‐Conjugated Tetrakis (4‐Aminophenyl) Porphyrin

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    Porphyrin complexes have been widely studied as promising electrode material in diverse energy storage systems and chemistries. However, like other organic electrodes, porphyrins often suffer from low conductivity and, consequently, require a significant amount (typically 40 %) of electrochemically inactive conductive carbon that occupies volume and mass without storing energy. In this study, we investigate [5,10,15,20 tetrakis(4-aminophenyl)-porphyrin] (TAPP) and its metal complexes as redox-active cathode materials to address the aforementioned issues. The lithium-ion cells prepared with a high content of CuTAPP active material (70 wt %) demonstrate a stable discharge capacity of ∼120 mAh/g when cycling with a constant current density of 1000 mA/g. The material also showed superior rate capability, e. g., ∼60 mAh/g at 8 A/g. The results of DFT calculations and experimental analysis indicate that the degree of planarity of the metalloporphyrins directly correlates to their cycling stability. Moreover, the contribution from the central metal redox during the cycling is found to be the reason for the significantly higher performance of the Cu-complex compared to the metal-free complex. The findings of this study show a general approach for facing common conductivity challenges of organic electrodes and open up a pathway for practical application of organics electrode materials in energy storage application

    Estimating inert gas bubbling from simple SCUBA diving parameters

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    Inert gas bubbles frequently occur in SCUBA divers' vascular systems, eventually leading to decompression accidents. Only in professional settings, dive profiles can be adjusted on individual basis depending on bubble grades detected through ultrasonography. A total of 342 open-circuit air dives following sports diving profiles were assessed using echocardiography. Subsequently, (Eftedal-Brubakk) bubble grades were correlated with dive and individual parameters. Post-dive cardiac bubbles were observed in 47% of all dives and bubble grades were significantly correlated with depth (r=0.46), air consumption (r=0.41), age (r=0.25), dive time (r=0.23), decompression diving (r=0.19), surface time (r=- 0.12). Eftedal-Brubakk categorical bubble grades for sports diving with compressed air can be approximated by bubble grade = (age*50-1 - surface time*150-1+maximum depth*45-1+air consumption*4500-1)2 (units in years, hours, meter, and bar*liter; R2=0.31). Thus, simple dive and individual parameters allow reasonable estimation of especially relevant medium to higher bubble grades for information on relevant decompression stress after ascent. Echo bubble grade 0 is overestimated by the formula derived. However, echo might fail to detect minor bubbling only. The categorical prediction of individual decompression stress with simple bio and dive data should be evaluated further to be developed towards dive computer included automatic ex-post information for decision-making on individual safety measures.info:eu-repo/semantics/publishedVersio

    Transversus Abdominis Plane Catheter Bolus Analgesia after Major Abdominal Surgery

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    Purpose. Transversus abdominis plane (TAP) blocks have been shown to reduce pain and opioid requirements after abdominal surgery. The aim of the present case series was to demonstrate the use of TAP catheter injections of bupivacaine after major abdominal surgery. Methods. Fifteen patients scheduled for open colonic resection surgery were included. After induction of anesthesia, bilateral TAP catheters were placed, and all patients received a bolus dose of 20 mL bupivacaine 2.5 mg/mL with epinephrine 5 μg/mL through each catheter. Additional bolus doses were injected bilaterally 12, 24, and 36 hrs after the first injections. Supplemental pain treatment consisted of paracetamol, ibuprofen, and gabapentin. Intravenous morphine was used as rescue analgesic. Postoperative pain was rated on a numeric rating scale (NRS, 0–10) at regular predefined intervals after surgery, and consumption of intravenous morphine was recorded. Results. The TAP catheters were placed without any technical difficulties. NRS scores were ≤3 at rest and ≤5 during cough at 4, 8, 12, 18, 24, and 36 hrs after surgery. Cumulative consumption of intravenous morphine was 28 (23–48) mg (median, IQR) within the first 48 postoperative hours. Conclusion. TAP catheter bolus injections can be used to prolong analgesia after major abdominal surgery

    Cosmic rays in astrospheres

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    Cosmic rays passing through large astrospheres can be efficiently cooled inside these "cavities" in the interstellar medium. Moreover, the energy spectra of these energetic particles are already modulated in front of the astrospherical bow shocks. We study the cosmic ray flux in and around lambda Cephei as an example for an astrosphere. The large-scale plasma flow is modeled hydrodynamically with radiative cooling. We studied the cosmic ray flux in a stellar wind cavity using a transport model based on stochastic differential equations. The required parameters, most importantly, the elements of the diffusion tensor, are based on the heliospheric parameters. The magnetic field required for the diffusion coefficients is calculated kinematically. We discuss the transport in an astrospheric scenario with varying parameters for the transport coefficients. We show that large stellar wind cavities can act as sinks for the galactic cosmic ray flux and thus can give rise to small-scale anisotropies in the direction to the observer. Small-scale cosmic ray anisotropies can naturally be explained by the modulation of cosmic ray spectra in huge stellar wind cavities

    Erector Spinae Plane Block for Elective Laparoscopic Cholecystectomy in the Ambulatory Surgical Setting

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    Postoperative pain after laparoscopic cholecystectomy can be severe. Despite multimodal analgesia regimes, administration of high doses of opioids is often necessary. This can further lead to several adverse effects such as drowsiness and respiratory impairment as well as postoperative nausea and vomiting. This will hinder early mobilization and discharge of the patient from the day surgery setting and is suboptimal in an Early Recovery after Surgery setting. The ultrasound-guided Erector Spinae Plane (ESP) block is a novel truncal interfascial block technique providing analgesia of the thoracic or abdominal segmental innervation depending on the level of administration. Local anesthetic penetrates anteriorly presumably through the costotransverse foramina to the paravertebral space. We demonstrate the analgesic efficacy of the ESP block in a case series of three patients scheduled for ambulatory laparoscopic cholecystectomy

    Flexibilisierung der Haushaltsnachfrage durch ein Photovoltaik-Batteriespeichersystem und ein Elektrofahrzeug = Flexible household load by solar energy storage and EV

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    Die Flexibilität der elektrischen Haushaltsnachfrage wird sich mit Photovoltaik-Batterie-speichersystem (PV-Speicher) und Elektrofahrzeug deutlich steigern und kann den Verlauf der Stromnachfrage und die Erlöse für Versorger signifikant verändern. Mit einem techno-ökonom¬ischen Optimierungsmodell solcher Haushalte zeigen wir die Wirtschaftlichkeit dieser PV-Speicher-Systeme – in wenigen Jahren sogar ohne Förderung. Mit Demand Response Maßnahmen oder speziellen Tarifen lässt sich die flexible Nachfrage seitens des Energie-versorgers beeinflussen. Insbesondere gesteuertes Laden des Elektrofahrzeugs hat einen erheblichen Einfluss auf das Ergebnis
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