Fachbereich Technik
Refine
Document Type
- Article (31)
- Conference Proceeding (21)
- Book (2)
- Preprint (2)
Keywords
- Cloud computing (4)
- Cyber-physical systems (2)
- In-network processing (2)
- Industrial Cyber-physical Systems (2)
- Network components (2)
- Network design principles (2)
- Network protocols (2)
- Scenario Mining (2)
- Security (2)
- infrared thermography (2)
Institute
- Fachbereich Technik (56)
Value delivery is becoming an important asset for an organization due to increasing competition in industry. Therefore, companies apply Agile Software Development (ASD) to be more competitive and reduce time to market. Using ASD for the development of systems implies that established approaches of Requirements Engineering (RE) undergo some changes in order to be more flexible to changing requirements. To this end, the field of agile RE is emergent and different process models for agile RE have arisen. The aim of this paper is to build an abstract layer about the variety of existing process models by means of a metamodel for agile RE. It has been created in several iterations and relies on the evaluation of related process models. Furthermore , we have derived process models for agile RE in industry by presenting instances of the metamodel in two different cases: one is based on Scrum whereas the other is based on Kanban. This paper contributes to the software development body of knowledge by delivering a metamodel for agile RE that supports researchers and practitioners modeling and improving their own process models. We can conclude that the agile RE metamodel is highly relevant for the industry as well as for the research community, since we have derived it following empirical research in the field of ASD.
Background
Wastewater treatment plants are known as major sources for the release of micropollutants and bacteria into surface waters. To reduce this contaminant and microbial input, new technologies for effluent treatment have become available. The present paper reports the chemical, microbiological, biochemical, and biological effects of upgrading a wastewater treatment plant (WWTP) with a powdered activated carbon stage in the catchment area of the Schussen River, the largest German tributary of Lake Constance. Data were obtained prior to and after the upgrade between 2011 and 2017.
Results
After the upgrading, the release of antibiotic resistant and non-resistant bacteria, micropollutants, and their effect potentials was significantly lower in the effluent. In addition, in the Schussen River downstream of the wastewater treatment plant, reduced concentrations of micropollutants were accompanied by both a significantly improved health of fish and invertebrates, along with a better condition of the macrozoobenthic community.
Conclusions
The present study clearly provides evidence for the causality between a WWTP upgrade by powdered activated carbon and ecosystem improvement and demonstrates the promptness of positive ecological changes in response to such action. The outcome of this study urgently advocates an investment in further wastewater treatment as a basis for decreasing the release of micropollutants and both resistant and non-resistant bacteria into receiving water bodies and, as a consequence, to sustainably protect river ecosystem health and drinking water resources for mankind in the future.
Propionate is an important intermediate in the anaerobic mineralization of organic matter. In methanogenic environments, its degradation relies on syntrophic associations between syntrophic propionate-oxidizing bacteria (SPOB) and Archaea. However, only 10 isolated species have been identified as SPOB so far. We report syntrophic propionate oxidation in thermophilic enrichments of Candidatus Syntrophosphaera thermopropionivorans, a novel representative of the candidate phylum Cloacimonetes. In enrichment culture, methane was produced from propionate, while Ca. S. thermopropionivorans contributed 63% to total bacterial cells. The draft genome of Ca. S. thermopropionivorans encodes genes for propionate oxidation via methymalonyl-CoA. Phylogenetically, Ca. S. thermopropionivorans affiliates with the uncultured Cloacimonadaceae W5 and is more distantly related (86.4% 16S rRNA gene identity) to Ca. Cloacimonas acidaminovorans. Although Ca. S. thermopropionivorans was enriched from a thermophilic biogas reactor, Ca. Syntrophosphaera was in particular associated with mesophilic anaerobic digestion systems. 16S rRNA gene amplicon sequencng and a novel genus-specific quantitative PCR assay consistently identified Ca. Syntrophosphaera/Cloacimonadaceae W5 in 9 of 12 tested full-scale biogas reactors thereby outnumbering other SPOB such as Pelotomaculum, Smithella and Syntrophobacter. Taken together the ubiquity and abundance of Ca. Syntrophosphaera, those SPOB might be key players for syntrophic propionate metabolism that have been overlooked before.
Die anaerobe Vergärung von Bioabfällen erzeugt nachhaltig Bioenergie und verringert Umweltbelastungen. Die acetogene Gärphase wurde mit dem Anaerobic Digestion Model No. 1 (ADM1) modelliert, das um drei Gattungen Propionat-oxidierender Bakterien und zwei Varianten des Propionatabbaus, den Methyl-Malonyl-CoA- und C6-Dismutase-Weg, erweitert wurde. Die kinetischen Parameter für die anaerobe Propionat-Oxidation wurden mit definierten Trikulturen aus den drei Propionat-oxidierenden Gattungen mit hydrogenotrophen und acetotrophen methanogenen Archaea bestimmt und in das ADM1 implementiert, woraus das verbesserte Modell ADM1xpro resultierte.
Background: Anaerobic digestion (AD) is a globally important technology for effective waste and wastewater management. In AD, microorganisms interact in a complex food web for the production of biogas. Here, acetoclastic methanogens and syntrophic acetate-oxidizing bacteria (SAOB) compete for acetate, a major intermediate in the mineralization of organic matter. Although evidence is emerging that syntrophic acetate oxidation is an important pathway for methane production, knowledge about the SAOB is still very limited.
Results: A metabolic reconstruction of metagenome-assembled genomes (MAGs) from a thermophilic solid state biowaste digester covered the basic functions of the biogas microbial community. Firmicutes was the most abundant phylum in the metagenome (53%) harboring species that take place in various functions ranging from the hydrolysis of polymers to syntrophic acetate oxidation. The Wood-Ljungdahl pathway for syntrophic acetate oxidation and corresponding genes for energy conservation were identified in a Dethiobacteraceae MAG that is phylogenetically related to known SAOB. 16S rRNA gene amplicon sequencing and enrichment cultivation consistently identified the uncultured Dethiobacteraceae together with Syntrophaceticus, Tepidanaerobacter, and unclassified Clostridia as members of a potential acetate-oxidizing core community in nine full-scare digesters, whereas acetoclastic methanogens were barely detected.
Conclusions: Results presented here provide new insights into a remarkable anaerobic digestion ecosystem where acetate catabolism is mainly realized by Bacteria. Metagenomics and enrichment cultivation revealed a core community of diverse and novel uncultured acetate oxidizing bacteria and point to a particular niche for them in dry fermentation of biowaste. Their genomic repertoire suggests metabolic plasticity besides the potential for syntrophic acetate oxidation.
Anaerobic digestion of biowaste not only reduces environmental burden but also plays an important role for sustainable energy supply. For process optimization simulation based on the Anaerobic Digestion Model No. 1 (ADM1) is commonly used.
The ADM1 was extended to include the known three genera of propionate oxidizing bacteria (POB) and the two routes of propionate degradation (methyl-malonyl CoA and C6-dismutation pathway). Kinetic parameters for anaerobic propionate oxidation by single strains of the three propionate oxidizing genera were determined from defined tri-cultures of the POB with hydrogenotrophic and acetotrophic methanogens and implemented into ADM1. The such improved model ADM1xpro was evaluated with operational data from a full scale wet biowaste digestion plant. Predicted amounts of biogas and composition with ADM1xpro (2201 m³ d−1, 68.1 % CH4 and 31.9 % CO2) correlated well with full-scale process data (2171 m³ d−1, 67.5 % CH4 and 31.9 % CO2).
This work presents an investigation on different methods for the calculation of the angle of attack and the underlying induced velocity on wind turbine blades using data obtained from three-dimensional Computational Fluid Dynamics (CFD). Several methods are examined and their advantages, as well as shortcomings, are presented. The investigations are performed for two 10 MW reference wind turbines under axial inflow conditions, namely the turbines designed in the EU AVATAR and INNWIND.EU projects. The results show that the evaluated methods are in good agreement with each other at the mid-span, though some deviations are observed at the root and tip regions of the blades. This indicates that CFD results can be used for the calibration of induction modeling for Blade Element Momentum (BEM) tools. Moreover, using any of the proposed methods, it is possible to obtain airfoil characteristics for lift and drag coefficients as a function of the angle of attack.
This paper presents a fluid-structure coupled simulation tool for high-fidelity simulations of wind turbine rotors. Coupling the open source Computational Fluid Dynamics (CFD) code OpenFOAM and the inhouse structural solver BeamFOAM, the developed tool allows the analysis of flexible wind turbines blades by means of CFD without a significant increase in computational costs. To demonstrate the capabilities of the coupled solver, the aero-elastic response of the NREL 5 MW reference wind turbine is computed for various conditions and specific results are compared to findings of other authors. The solver framework is then used to investigate the effect of blade deformations on aerodynamic key parameters such as power, thrust and sectional forces. It is shown, that the structural deformations have a clear influence on the aerodynamic rotor performance. Especially for the case of yawed inflow, significant implications can be observed in terms of loads and local induction factors. Compared to the fluid-structure coupled framework, the rigid CFD solver underpredicts the forces acting on the blades for most of the cases. Consequently, the presented results are expected to contribute to improve the correction models used in aerodynamic models of lower fidelity like those based on the Blade Element Momentum theory.
The analysis of wind turbine aerodynamics requires accurate information about the axial and tangential wake induction as well as the local angle of attack along the blades. In this work we present a new method for obtaining them conveniently from the velocity field. We apply the method to the New Mexico particle image velocimetry (PIV) data set and to computational fluid dynamics (CFD) simulations of the same turbine. This allows the comparison of experimental and numerical results of the mentioned quantities on a rotating wind turbine. The presented results open up new possibilities for the validation of numerical rotor models.
Navier-Stokes actuator disc models have become a mature methodology for investigating wind turbine rotor performance with numerous articles published annually making use of this approach. Despite their popularity, their ability to predict near wake expansion remains questionable. The objective of this paper is to analyse the predictive ability of actuator disc models and compare results with other popular types of codes. The methodology employs the use of an actuator disc Computational Fluid Dynamics approach to model an actuator disc and a real (finite bladed) turbine case. Results are validated with existing experimental data. In addition, results from an actuator line model with and without tip corrections and a 3D vortex panel method are presented to aid the discussion. Results show that all models give a poor wake expansion prediction particularly in the inboard to mid-board areas. A good prediction is found in the outboard regions. In addition, contrary to the well known positive effects of tip corrections on load prediction, this work shows that this does not bring any particular benefit on wake expansion prediction. The conclusions from this work help to guide the use of actuator disc models in more complex flow scenarios including floating offshore wind turbine analysis.