Simulation strategies for complex turbulent flows

Computational fluid dynamics in conjunction with the Reynolds-Averaged Navier-Stokes approach is nowadays routinely employed in a large variety of engineering andindustrial applications despite some well-known reliability issues in more complex flows. In this study, the performance of a state-of-the-art Explicit-Algebraic-StressModel (EASM) and a promising elliptic-blending approach is assessed on a range of test cases to predict complex turbulent flows. In an attempt to improve the quality of the predictions, near-wall-anisotropy modifications are introduced to the EASM, which provide better predictions for the Reynolds-stress and anisotropy tensor close to solid walls. In addition, a novel elliptic-blending RANS model is presented, which is based on the inverse turbulence time scale w, and which is equipped with a non-linear constitutive stress-strain relationship. The coefficients of the non-linear stress-strain relationship are obtained from the explicit solution of a Second-Moment Closure in the limit of weak equilibrium, and by imposing an internal consistency constraint and near-wall-anisotropy modifications, such that the highly anisotropic state of turbulence and the limiting two-component state is correctly reproduced at solid boundaries. The performance of the modified EASM and the novel elliptic-blending model are illustrated and assessed for a range of complex turbulent flows. It is expected that, due to ever increasing computational resources, unified or hybrid RANS/LES approaches will slowly penetrate into engineering applications where improved accuracy and reliability is needed. For this reason, a unified RANS/LES/DNS framework is presented, which is expected to provide the required amount of turbulence modelling for any mesh resolution and seamlessly operates between RANS and DNS mode. This is achieved by a revised Flow Simulation Methodology where the turbulence modelling contribution of a RANS model is rescaled using a damping function. The Flow Simulation Methodology is operating in conjunction with a newly developed damping function and a tailored convection discretisation scheme. In addition, a thorough calibration study is performed, which ensures proper turbulence resolving capabilities. It is conjectured that a sophisticated RANS model will also improve the overall quality of the predictions of any hybrid RANS/LES model. For this reason, the new elliptic-blending RANS model is incorporated, together with two successively simpler turbulence models, into the unified RANS/LES/DNS framework and the performance are assessed on a range of test cases, and compared to other widely used hybrid RANS/LES methods

Entwicklung eines schnellen Bio-Tests zur Untersuchung des Wirkungs-potentials von mikrobiellen Pflanzenstärkungsmitteln

Plant-growth-promoting soil microorganisms are increasingly distributed on the world market. Nutrient mobilization, stimulation of root growth, enhanced resistance to envi-ronmental stress factors are discussed as possible mechanisms. These assumptions are based only on scarce scientific evidence due to limited reproducibility of pot and field experiments, limited information concerning the conditions for successful applica-tion, limited standardization of inoculum preparation and quality. Thus, the develop-ment of rapid screening tests is to demonstrate the principle effectiveness of biofertil-izers prior to set-up of labourous pot or field experiments is urgently required. In this study, a rapid bio-test with cucumber (Cucumis sativa L.) as an indicator plant was developed to evaluate the effectiveness of five commercial biofertilizers based on Trichoderma spp. and Bacillus spp. (Biohealth-G, Biohealth-WSG, Biomex, Vitalin T50 and SP11) using germination rate, root and shoot biomass, maximum root length, and leaf area as test parameters. The experiment was repeated twice with 6 replicates in hydroponic culture under controlled conditions (pH 5.5, 22° C; Light: 230 mmol cm2 sec-1). Biofertilizers were applied at the rate of 3 g per 2.5 l mineral nutrient solution. Germination rate was increased by 20 - 25% in all biofertilizer treatments compared to the control. After 2 weeks culture period, root dry weight and leaf area of Biohealth-G, Vitalin T50, SP-11 and Biomex-treated cucumber seedlings were significantly in-creased. Biohealth-G and Vitalin T50 showed significantly higher main root length and Biohealth-G higher shoot dry weight than the remaining treatments, while Biohealth-WSG did not cause differences compared to untreated control plants. The pathogen-antagonistic potential of Trichoderma strains can be easily tested by co-inoculation with the pathogenic fungus Gaeumannomyces graminis on malt extract peptone agar plates. The results suggest that the activity potential of different Trichoderma-based biofertilizers could be easily screened by using the described bio-test with cucumber seedlings

The Effect of Social Distance in Donation-Based Crowdfunding

Crowdfunding offers an innovative approach to financing projects by facilitating many individuals and organizations to contribute, often small amounts, to these projects. In the context of donation-based crowdfunding, we study how social distance affects average donations. Drawing on construal level theory, we argue that project images featuring humans reduce the social distance for donors because they can identify with the recipients; thus, these campaigns are more concrete, and donors give more. To test the effect of social distance using (human) project images on average donations, we conducted two studies, one observational and one experimental study. In both studies, we show that projects, whose images feature humans, receive higher donations

Automatic Extrinsic Self-Calibration of Mobile Mapping Systems Based on Geometric 3D Features

Mobile Mapping is an efficient technology to acquire spatial data of the environment. The spatial data is fundamental for applications in crisis management, civil engineering or autonomous driving. The extrinsic calibration of the Mobile Mapping System is a decisive factor that affects the quality of the spatial data. Many existing extrinsic calibration approaches require the use of artificial targets in a time-consuming calibration procedure. Moreover, they are usually designed for a specific combination of sensors and are, thus, not universally applicable. We introduce a novel extrinsic self-calibration algorithm, which is fully automatic and completely data-driven. The fundamental assumption of the self-calibration is that the calibration parameters are estimated the best when the derived point cloud represents the real physical circumstances the best. The cost function we use to evaluate this is based on geometric features which rely on the 3D structure tensor derived from the local neighborhood of each point. We compare different cost functions based on geometric features and a cost function based on the Rényi quadratic entropy to evaluate the suitability for the self-calibration. Furthermore, we perform tests of the self-calibration on synthetic and two different real datasets. The real datasets differ in terms of the environment, the scale and the utilized sensors. We show that the self-calibration is able to extrinsically calibrate Mobile Mapping Systems with different combinations of mapping and pose estimation sensors such as a 2D laser scanner to a Motion Capture System and a 3D laser scanner to a stereo camera and ORB-SLAM2. For the first dataset, the parameters estimated by our self-calibration lead to a more accurate point cloud than two comparative approaches. For the second dataset, which has been acquired via a vehicle-based mobile mapping, our self-calibration achieves comparable results to a manually refined reference calibration, while it is universally applicable and fully automated

Education and Research in the context of the digital and ecological transformation of agriculture in the Banat Region and Baden-Württemberg - towards resource efficiency and resilience

Ziel des Banat Green Deal Projekts GreenERDE (Bildung und Forschung im Kontext der digitalen und ökologischen Transformation des Agrarbereichs im Banat und Baden-Württemberg - auf dem Weg zu Ressourceneffizienz und Resilienz) war es entsprechend der landestypischen Schwerpunkte Berufliche Bildung, Umwelt, Wirtschaft und Capacity Building das bisherige Engagement Baden-Württembergs im landwirtschaftlichen Berufsbildungszentrum Voiteg mit einer nachhaltigen Entwicklungsstrategie zur Stärkung der Wettbewerbsfähigkeit des Agrarbereichs im rumänischen Banat und benachbarter Regionen mit innovativen fachlichen und gleichzeitig soziokulturell interessanten Inhalten zu verbinden. Das im Rahmen des Projekts durchgeführte Fortbildungsprogramm Landwirtschaft in Verantwortung für unsere gemeinsame Welt, zielt auf den Wissens- und Erfahrungstransfer unter Landwirten und anderen interessirten Personen in der Banat-Region, Rumänien und anderen Teilen der Welt ab. Aktuelle und zukünftige Herausforderungen, wie die ökologische Umstellung und die digitale Transformation der landwirtschaftlichen Produktion, aber auch soziale, wirtschaftliche und kulturelle Aspekte wurden adressiert. Innovatives und relevantes Wissen aus Praxis, Forschungs- oder Entwicklungsprojekten in ganz Europa und anderen Kontinenten wird in einem Trainingsformat für interessierte Teilnehmer präsentiert.The Banat Green Deal project "GreenERDE" (Education and Research in the context of the digital and ecological transformation of agriculture in the Banat Region and Baden-Württemberg - towards resource efficiency and resilience) aimed to strengthen the the competitiveness of the agricultural sector in the Romanian Banat, Baden-Württemberg and neighboring regions with innovative technical and at the same time socio-cultural connect interesting content. The advanced training program Farming in Responsibility for Our Common World carried out as part of this project aims at the transfer of knowledge and experience among farmers and other interested persons. Current and future challenges, such as ecological conversion and the digital transformation of agricultural production, but also social, economic and cultural aspects were addressed. Innovative and relevant knowledge from practice, research or development projects throughout Europe and other continents is presented

Bio-effectors for improved growth, nutrient acquisition and disease resistance of crops

Recent scientific approaches to sustain agricultural production in face of a growing world food demand, limited natural resources, and ecological concerns have been focusing on biological processes to support soil fertility and healthy plant growth. In this context, the use of bio-effectors, comprising living (micro-) organisms and active natural compounds, has been receiving increasing attention. In contrast to conventional fertilizers and pesticides, the effectiveness of bio-effectors is essentially not based on the substantial direct input of mineral plant nutrients, neither in inorganic nor organic forms, nor of a-priori toxic compounds. Their direct or indirect effects on plant performance are rather based on the functional implementation or activation of biological mechanisms, in particular those interfering with soil-plant-microbe interactions. The general objective of the present research work was to improve the empirical and conceptual understanding concerning the utilization of bio-effectors in agricultural practice, following the principles of plant growth stimulation, bio-fertilization and bio-control. One main aspect of investigation was the application of bio-effectors to improve the efficiency of phosphorus (P) acquisition by the plant. Promising bio-preparations based on microbial inoculants (e.g. Bacillus, Pseudomonas, Trichoderma species) as well as natural compounds (e.g. algae extracts, humic acids) were tested in screening assays, greenhouse, and field experiments to characterize their potential effectiveness under varying environmental conditions. The most significant effects on plants appeared under severely low phosphate availability, but even under controlled conditions, bio-effectors required a narrow range of conductive environmental settings to reveal their potential effectiveness. Another focus of research was the application of bio-effectors to control soil borne pathogens, which typically appear in unsound crop rotations. Emphasis was set on take-all disease in wheat induced by the fungus Gaeumannomyces graminis. While the effectiveness of oat precrops to control take-all in subsequent wheat has been attributed to microbial changes and enhanced manganese (Mn) availability in soils, the take-all fungus is known to decrease the availability of Mn by oxidation. Against this background, the effectiveness of oat precrops and alternative crop management strategies to improve the Mn status and suppress the severity of take-all in wheat was investigated under controlled and field conditions. In conclusion, none of the tested supplemental treatments, such the application of microbial bio-effectors, stabilized ammonium or manganese fertilizers, could fully substitute for the multiple effectiveness of oat precrops, which was further confirmed by the results of a field experiment. Finally, some general conclusions and perspectives are summarized. Selected bio-effectors showed a strong capacity to improve the nutrient acquisition and healthy growth of crop plants under controlled conditions, but not in field experiments. However, even under controlled conditions the strongest effects occurred when plants were exposed to abiotic or biotic stresses, such as severely limited P availability or pathogen infestation of the soil substrate, still restricting plant growth to unproductive levels. Facing this situation, there is no perspective to improve the field efficiency of promising bio-effectors applications as a stand-alone approach. The only chance to develop viable alternatives to the conventional use of fertilizers or pesticides, for an ecological intensification of agriculture that maintains high yield levels, seems to be a reasonable integration of bio-effectors into the whole crop management of sound agricultural practice.Angesichts eines weltweit wachsenden Bedarfs an Nahrungsmitteln, begrenzter natürlicher Ressourcen und ökologischer Probleme streben neuere wissenschaftliche Ansätze zur nachhaltigen Gestaltung der Landwirtschaft verstärkt die Nutzung biologischer Prozesse zur Föderung der Bodenfruchtbarkeit und eines gesunden Kulturpflanzenwachstums an. In diesem Zusammenhang hat der Einsatz von Bio-Effektoren, einschließlich lebender (Mikro-)Organismen und wirkaktiver Naturstoffe, wachsendes Interesse gefunden. Im Gegensatz zu konventionellen Düngemitteln und Pestiziden beruht die Wirksamkeit von Bio-Effektoren nicht auf dem substantiellen Direkteintrag von Pflanzennährstoffen, weder in anorganischer noch organischer Form, noch von a priori toxischen Stoffen. Die direkten oder indirekten Wirkungen von Bio-Effektoren auf die Pflanze basieren vielmehr auf der Implementierung oder Aktivierung von biologischen Wirkungsmechanismen, insbesondere solcher die mit den Interaktionen von Boden, Pflanze und Mikroorganismen interferieren. Ziel der vorliegenden Arbeit war es, das Verständnis zur Nutzung von Bio-Effektoren in der landwirtschaftlichen Praxis anhand der prinzipiellen Wirkungskategorien von direkter Stimulans des Pflanzenwachstums, biologischer Pflanzenernährung (bio-fertilization) und biologischem Pflanzenschutz (bio-control) zu erweitern. Ein Hauptaspekt galt der Anwendung von Bio-Effektoren um die Aneignungseffizienz von Phosphor (P) durch die Pflanze zu steigern. Aussichtsreiche Präparate, basierend auf mikrobiellen Inokula (z.B. Bacillus, Pseudomonas, Trichoderma Spezies) als auch Naturstoffen (z.B. Algenextrakte, Huminsäuren), wurden in Screeningassays, Gewächshaus- und Feldversuchen getestet um ihr Wirkungspotential unter variablen Umweltbedingungen zu charakterisieren. Die stärksten Effekte traten unter Bedingungen mit sehr geringer Phosphatverfügbarkeit auf, jedoch selbst unter kontrollierten Bedingungen war der Einfluss förderlicher und teilweise eng bestimmter Umweltfaktoren notwendig um die Wirksamkeit von Bio-Effektoren zu zeigen. Ein weiteres Thema war der Einsatz von Bio-Effektoren zur Bekämpfung bodenbürtiger Krankheitserreger, welche durch unausgewogene Fruchtfolgen gefördert werden. Die Untersuchungen befassten sich insbesondere mit der Schwarzbeinigkeit des Weizens, einer bedeutenden Wurzelkrankheit hervorgerufen durch den Pilz Gaeumannomyces graminis. Eine effektive Vorfrucht zur Bekämpfung der Schwarzbeinigkeit ist Hafer, was in Zusammenhang mit mikrobiellen Veränderungen im Boden und einer erhöhten Verfügbarkeit von Mangan (Mn) für die Folgefrucht Weizen gestellt wurde. Vor diesem Hintergrund wurde die Wirksamkeit von Hafer als Vorfrucht im Vergleich mit alternativen Maßnahmen des pflanzenbaulichen Managements zur Steigerung der Mn-Versorgung und Bekämpfung der Schwarzbeinigkeit in Weizen untersucht. Fazit war, daß keine der getesten Alternativmaßnahmen, wie die Anwendung mikrobieller Bio-Effektoren, stabilisierten Ammonium- oder Mangandüngers, die vielseitige Vorfruchtwirkung von Hafer vollständig substituieren konnte, was auch durch die Ergebnisse eines Feldversuches bestätigt wurde. Abschließend folgen generelle Schlussfolgerungen aus der vorliegenden Arbeit und sich daraus ergebende Perspektiven zur Nutzung von Bio-Effektoren. Ausgewählte Bio-Effektoren zeigten unter kontrollierten Bedingungen ein hohes Wirkungspotential zur Förderung der Nährstoffaneignung und des gesunden Wachstums von Kulturpflanzen, nicht jedoch in Feldversuchen. Zudem waren die stärksten Effekte dann zu beobachten, wenn die Pflanzen abiotischen oder biotischen Stresssituationen, wie stark limitierter P-Verfügbarkeit oder einem pathogenbelasteten Bodensubstrat, ausgesetzt waren, welche das Pflanzenwachstum auch weiterhin auf ein unproduktives Maß beschränkten. Diese Ergebnisse eröffnen keine Perspektive den praktischen Nutzen von Bio-Effektoren durch Einzelmaßnahmen zu steigern. Vielmehr schein der einzig erfolgversprechende Ansatz leistungsfähige Alternativen zum konventionellen Einsatz von Düngemitteln und Pestiziden für eine ökologische Intensivierung der Agrarproduktion auf hohem Ertragsniveau zu entwickeln, eine sinnvolle Integration von Bio-Effektoren in das gesamte pflanzenbauliche Management einer fachgerechten Landwirtschaft zu sein

Dichloridobis(methyl­amine-κN)boron(III) chloride

The title compound, C2H10BCl2N2 +·Cl− or [BCl2(H3CNH2)2]+·Cl−, is the first crystallographically characterized di(alkyl­amine)–BCl2 + salt. The B atom is tetra­hedrally coordinated by two Cl and two methyl­amine N atoms. In the crystal structure, the cations and anions inter­act via N—H⋯Cl hydrogen bonds (mean H⋯Cl = 2.40 Å), resulting in a layered structure

Improving fertilizer-depot exploitation and maize growth by inoculation with plant growth-promoting bacteria: from lab to field

Among other responses, plants tend to increase root growth to scavenge nutrients from more soil when soil nutrient concentrations are low. Placement of fertilizers near seeds or roots facilitates nutrient acquisition by target crop plants. Nevertheless, nutrient uptake from soil-placed fertilizer-depots depends on increased uptake rates and efficient spatial exploitation of the depot by roots. The aim of our study was to optimize exploitation of subsurface fertilizer-depots by inoculating the depot zone with promising plant growth-promoting microorganisms (PGPMs) as bio-effectors. If included in depots, root-attracting NH4+ or HPO42−/H2PO4− ions may also enhance rooting within the depot, which in turn improves survival and root colonization by inoculated PGPMs; a consequence of high levels of microbial nutrients exuded in densely rooted soil. We tested maize (Zea mays L.) in two greenhouse (pot and rhizobox) and two field experiments (2014 and 2015). A core treatment was NH4+-fertilizer placed as a subsurface depot (Depot). In the field, there was also NH4+- fertilizer broadcasted and incorporated in soil (Broad). Depot and Broad were each with PGPM as bio-effector (BE) or without (NoBE). Bio-effectors included: Pseudomonas sp. DSMZ 13134 (BE1) and Bacillus amyloliquefaciens FZB42 (BE2, only in field trials). In pots, Depot with BE1 led to 59 % higher shoot dry matter, 50 % higher shoot N content, and 64 % higher shoot P content than without PGPM. In rhizoboxes, higher root length density (RLD), lower rhizosphere pH, and higher BE1-colonization rate were measured in the fertilizer depot compared to the corresponding zone for controls with homogenous NO3− supply. Depot led to higher shoot N and P concentrations (+26.6 % N; +20.6 % P) and contents (+11.1 % N; +17.6 % P) than control. BE1 led to higher shoot N concentration (+13.5 %) than NoBE. In the field, fertilizer-depot soil had higher RLD than corresponding non-depot soil. BE1 led to doubled fertilizer-depot RLD in comparison to without (2014). In 2014, Depot led to 7.4 % higher grain yield than Broad (not statistically significant), whereas BE broadcast had no effect. In 2015, Depot led to 5.8 % higher fresh shoot biomass than Broad, below-seed placement of BE1 led to higher fresh (+7.1 %) and dry (+8.0 %) shoot biomass than NoBE. Results show promising growth-effects of Pseudomonas sp. DSMZ 13134 on field-grown maize