A Novel Approach to Generate Hourly Photovoltaic Power Scenarios

Photovoltaic power is playing an ever-increasing role in the energy mix of countries worldwide. It is a stochastic energy source, and simulation models are needed to establish reliable risk management. This paper presents a novel approach for simulating hourly solar irradiation and—as a consequence—photovoltaic power based on easily accessible data such as wind, temperature, and cloudiness. Solar simulations are generated via a multiplication factor that scales the maximum possible solar irradiation. Photovoltaic simulations are then derived using formulas that approximate the physical interdependencies. The resulting simulations are unbiased on an annual level and reasonably reflect historic irradiation movements. Interpreting our approach as a descriptive model, we find that error values vary over the year and with granularity. Errors are highest when considering hourly values in wintertime, especially in the morning or late afternoon

3D-Printing of Hierarchically Designed and Osteoconductive Bone Tissue Engineering Scaffolds

In Bone Tissue Engineering (BTE), autologous bone-regenerative cells are combined with a scaffold for large bone defect treatment (LBDT). Microporous, polylactic acid (PLA) scaffolds showed good healing results in small animals. However, transfer to large animal models is not easily achieved simply by upscaling the design. Increasing diffusion distances have a negative impact on cell survival and nutrition supply, leading to cell death and ultimately implant failure. Here, a novel scaffold architecture was designed to meet all requirements for an advanced bone substitute. Biofunctional, porous subunits in a load-bearing, compression-resistant frame structure characterize this approach. An open, macro- and microporous internal architecture (100 µm–2 mm pores) optimizes conditions for oxygen and nutrient supply to the implant’s inner areas by diffusion. A prototype was 3D-printed applying Fused Filament Fabrication using PLA. After incubation with Saos-2 (Sarcoma osteogenic) cells for 14 days, cell morphology, cell distribution, cell survival (fluorescence microscopy and LDH-based cytotoxicity assay), metabolic activity (MTT test), and osteogenic gene expression were determined. The adherent cells showed colonization properties, proliferation potential, and osteogenic differentiation. The innovative design, with its porous structure, is a promising matrix for cell settlement and proliferation. The modular design allows easy upscaling and offers a solution for LBDT

Schweizer M&A-Markt 2014 : Auf dem Gipfel angekommen ?

Das Jahr 2014 war ein Rekordjahr auf dem Schweizer M&A-Markt. So stieg die Anzahl der Transaktionen um 33% von 315 im Jahr 2013 auf nunmehr 420 an. Auch der Fünf-Jahres-Vergleich zeigt, dass die Anzahl angekündigter Deals die Werte aus den Jahren 2010 bis 2012 übertraf. Noch positiver fällt der Blick auf die Entwicklung des Dealvolumens im vergangenen Jahr aus, das zuletzt 188,1 Mrd. USD betrug. Damit lag der Wert aller Deals auf dem Schweizer M&A-Markt sogar noch deutlich über dem bisherigen Rekordhoch in Höhe von 116,5 Mrd. USD aus dem Jahr 2012. Gegenüber dem Vorjahr (33,2 Mrd. USD) hat sich das Transaktionsvolumen sogar mehr als verfünffacht

Columbus Eye: Interactive Earth Observation from the ISS in Class Rooms. GI_Forum|GI_Forum 2015 – Geospatial Minds for Society|

From May to November 2014, the Astronaut Alexander Gerst fascinated the German public with his live-impressions from the ISS. During his mission “Blue Dot”, he used twitter and social media to share his view on our planet with the interested public. Earth observation suddenly became a recurrent topic in the news when Gerst presented cities at night, the aurora borealis, or Gaza at war. At the same time, NASA attached four commercial off-theshelf (COTS) cameras to the European Columbus laboratory of the International Space Station (ISS) observing the Earth in high definition quality. Once installed, the main purposes of NASA’s high definition earth viewing (HDEV) mission experiment started, i.e. testing the suitability of COTS HD cameras for upcoming space missions to Moon and Mars. The German educational project “Columbus Eye – Live-Imagery of the ISS in Schools” funded by the German Aerospace Center (DLR) is the exclusive European partner of the HDEV experiment. Accomplished by the University of Bonn, the project is in charge of filing and publishing the HDEV data in a web portal, and, thus, making the data accessible to the public. However, the main goal of Columbus Eye is the didactical valorisetion of the HDEV data for a sustainable use in secondary school lessons. Hence, earth observation from the ISS carries on, even after Gerst returned to Earth. The fascinating views from above provide the basis for mediating knowledge about space travels and remote sensing linked to the Geographical curriculum. The short paper aims to present a) the didactical concept of Columbus Eye, b) the implementation of a learning portal about HDEV, and c) first experiences obtained during a nationwide road show in schools

Tailoring and Investigation of Defined Porosity Properties in Thin-Walled 316L Structures using Laser-Based Powder Bed Fusion

Process engineering applications, which require a defined mass transport, call for thin-walled structures with a defined open porosity. Powder bed fusion by a laser beam (PBF-LB) is investigated as a potential manufacturing method using stainless steel 316L to produce such structures. The total porosity was determined by weighing and volume measurement. The influence of the process parameters laser power, scan speed and hatch distance on porosity was investigated by means of a design of experiments (DoE) approach using a central composite design (CCD). A statistically significant regression model was developed to allow a prediction of the porosity values within the design space. To determine the distribution and size of porous sections, computed tomography and a microscope in transmitted light mode were used as well. Permeability was also analyzed. Within the design space, a permeability coefficient of 2258.26 E-12 m2 was achieved with a maximum porosity value of 19.00%. With the help of the CT analysis, it was determined that for area laser energy densities between 0.625 and 0.744 J/mm2, the average pore size from 4728.57 to 9841.38 \textgreekmm2 can be adapted

Federated learning vector quantization for dealing with drift between nodes

Vaquet V, Hinder F, Brinkrolf J, Menz P, Seiffert U, Hammer B. Federated learning vector quantization for dealing with drift between nodes. Presented at the 30th European Symposium on Artificial Neural Networks, Computational Intelligence and Machine Learning, ESANN 2022, Bruges

Es macht einen Unterschied – eine Differenz thematisierende, (de)konstruierende Lesehilfe

Fegter S, Hoffarth B, Klingler B, Machold C, Menz M. Es macht einen Unterschied – eine Differenz thematisierende, (de)konstruierende Lesehilfe. In: Kessl F, Plößer M, eds. Differenzierung, Normalisierung, Andersheit. Soziale Arbeit als Arbeit mit den Anderen. Wiesbaden: VS Verlag für Sozialwissenschaften; 2010: 17-22

Rush hours in flower visitors over a day–night cycle

Most research on pollination has focussed on a subset of insect taxa within a narrow time window during daylight hours. As a consequence, we have a limited understanding of the diversity and activity of flower visitors during the night or belonging to taxa other than bees or syrphid flies. Here, we quantified the abundance and species richness of flower visitors in ruderal meadows over repeated 24-h cycles (i.e. day and night), and identified abiotic factors influencing these patterns. From the plant perspective, we investigated the likelihood of being visited by an insect across a 24-h cycle. Activity of flower-visiting insects never dropped to zero over 24-h. During the day, non-syrphid Diptera and Hymenoptera were the most abundant, and species-rich groups of flower visitors, Lepidoptera and Coleoptera during night. While two of the seven most frequently visited plant species were most likely to be visited during the day, five also had a high likelihood to be visited during the night. The abundance and species richness of flower visitors was positively related to temperature during both the day and the night, whereas there was only a positive relationship with brightness during the day. We conclude that non-syrphid Diptera and nocturnal flower visitors are currently underappreciated. As the latter seem to respond differently to abiotic factors compared to diurnal species, they may potentially increase response diversity and resilience of plant-pollinator communities. There is an urgent need to improve our understanding of their ecological role and potential decline due to global change

A novel approach to generate hourly photovoltaic power scenarios

Photovoltaic power is playing an ever-increasing role in the energy mix of countries worldwide. It is a stochastic energy source, and simulation models are needed to establish reliable risk management. This paper presents a novel approach for simulating hourly solar irradiation and—as a consequence—photovoltaic power based on easily accessible data such as wind, temperature, and cloudiness. Solar simulations are generated via a multiplication factor that scales the maximum possible solar irradiation. Photovoltaic simulations are then derived using formulas that approximate the physical interdependencies. The resulting simulations are unbiased on an annual level and reasonably reflect historic irradiation movements. Interpreting our approach as a descriptive model, we find that error values vary over the year and with granularity. Errors are highest when considering hourly values in wintertime, especially in the morning or late afternoon