Exploring the Groß Schönebeck (Germany) geothermal site using a statistical joint interpretation of magnetotelluric and seismic tomography models

Exploration for geothermal resources is often challenging because there are no geophysical techniques that provide direct images of the parameters of interest, such as porosity, permeability and fluid content. Magnetotelluric (MT) and seismic tomography methods yield information about subsurface distribution of resistivity and seismic velocity on similar scales and resolution. The lack of a fundamental law linking the two parameters, however, has limited joint interpretation to a qualitative analysis. By using a statistical approach in which the resistivity and velocity models are investigated in the joint parameter space, we are able to identify regions of high correlation and map these classes (or structures) back onto the spatial domain. This technique, applied to a seismic tomography-MT profile in the area of the Groß Schönebeck geothermal site, allows us to identify a number of classes in accordance with the local geology. In particular, a high-velocity, low-resistivity class is interpreted as related to areas with thinner layers of evaporites; regions where these sedimentary layers are highly fractured may be of higher permeability.     

Sustainability standards for bioenergy—A means to reduce climate change risks?

The paper discusses the importance of standards for sustainable bioenergy production. Sustainability of bioenergy production is crucial if bioenergy is supposed to contribute effectively to climate change mitigation. First, a brief overview of current bioenergy policies and of initiatives and legislation for bioenergy sustainability are given. Then, the authors show that under free market conditions undersupply of sustainable bioenergy will prevail. Two types of market failures are identified: information asymmetry and externalities in bioenergy production. Due to these market failures bioenergy is less sustainable than it could be. It is shown that mandatory certification and subsequent labeling can help to overcome the information asymmetry and lead to a more efficient market outcome since consumers can choose products according to their preferences. The authors conclude, however, that the existence of production externalities asks for stronger market intervention, for example in the form of binding minimum standards or taxes. The paper discusses the efficiency and feasibility of such policy measures and shows that mandatory certification combined with binding minimum standards can be an adequate policy choice to regulate the bioenergy market.     

Eigenschaften alter Eisen und Stähle und ihre adäquate Materialprüfung und Bewertung

Material properties of old iron and steel and related adequate material testing and rating. Numerous load carrying structures made of iron and steel during the period of time after 1840 are in use up to now in Germany and in other industrialised countries. They are still under traffic after decades or even centuries of service. Mostly, there is no need to replace them now. Only the lack of knowledge of the engineers involved in the investigation and rating of old structures is very often the only reason for their decommissioning. To some extent, the inadequate knowledge about the material properties of the iron and steel of the early times of engineering construction is the real reason of replacing some structures. There is real lack of knowledge about of how to perform material test and to interpret the results. After many years of being concerned with the problem under consideration, in close co-operation with colleagues from competent institutes, the author intends to present a state of technology reached in two centuries of intensive research and application in practice.     

Zum Einsatz von Verpresspfählen an Stelle von Verpressankern zur Rückverankerung von Spundwänden

Application of pressure-grouted piles instead of pressure-grouted anchors as bracings for sheet pile walls. Pressure-grouted piles are recently more and more often used instead of anchors as bracings for sheet pile walls. In Germany, the piles are mostly tested in the same way as anchors, i. e. according to DIN 4125. The load-deformation behaviour of pressure-grouted piles and anchors in sand during load testing and in the final state is investigated and compared. First, the different systems of both elements are described and the regulations according to the current standards are presented. Then calculation results obtained with the finite element method are presented. With respect to the final state, pressure-grouted piles show in usual load tests a significantly different, i. e. more favourable behaviour. The main reason for that is that in the load test, in contrast to the final state, anchor forces can be transferred to the soil inside the active sliding wedge. This effect is even enforced by a restraint between wall and soil due to the propping of the hydraulic jack for the test load against the wall. These effects must be considered in the evaluation of load test results with pressure-grouted piles.     

Management of complex data flows in the ASDEX Upgrade plasma control system

Establishing adequate technical and physical boundary conditions for a sustained nuclear fusion reaction is a challenging task. Phased feedback control and monitoring for heating, fuelling and magnetic shaping is mandatory, especially for fusion devices aiming at high performance plasmas. Technical and physical interrelations require close collaboration of many components in sequential as well as in parallel processing flows. Moreover, handling of asynchronous, off-normal events has become a key element of modern plasma performance optimisation and machine protection recipes.The manifoldness of plasma states and events, the variety of plant system operation states and the diversity in diagnostic data sampling rates can hardly be mastered with a rigid control scheme. Rather, an adaptive system topology in combination with sophisticated synchronisation and process scheduling mechanisms is suited for such an environment. Moreover, the system is subject to real-time control constraints: response times must be deterministic and adequately short.Therefore, the experimental tokamak device ASDEX Upgrade employs a discharge control system DCS, whose core has been designed to meet these requirements. In the paper we will compare the scheduling schemes for the parallelised realisation of a control workflow and show the advantage of a data-driven workflow over a managed workflow. The data-driven workflow as used in DCS is based on signals connecting process outputs and inputs. These are implemented as real-time streams of data samples. Consequently, real-time signal management forms the foundation of DCS. The paper explains the principal features such as tagged samples, signal groups, algorithmic blocks and processes as well as scheduling schemes which allow DCS control applications to be defined as self-contained modular building blocks glued together by a software framework.By virtue of this sound foundation, DCS is a mature but still evolving system for reliable, distributed control of an entire tokamak device coordinating and monitoring 20 diagnostic systems, 14 magnetic power supplies, 5 heating systems with a total power of more than 25 MW, 8 gas fuelling channels, a pellet injector and a killer gas gun.     

Numerical Modeling of Turbulent Melt Flow in a Continuous Casting Mold Affected by an Electromagnetic Brake

The current work combines numerical and experimental investigations based on a small-scale mockup using the eutectic alloy GaInSn.The jet flow discharging from the submerged entry nozzle was exposed perpendicularly to a DC magnetic field across the entire wide face of the mold.Numerical calculations were performed by using the commercial package CFX with an implemented RANS-SST turbulence model.The anisotropic properties of the MHD turbulence were taken into account by specific modifications of the turbulence model.The comparison between our numerical calculations and the experimental results shows a very well agreement.In particular,the modified RANS-SST turbulence model is capable to reconstruct the peculiar phenomenon of the excitation of non-steady,non-isotropic large-scale flow perturbations caused by the application of the DC magnetic field.Another important finding of our study is the feature that the electrical boundary conditions,namely the wall conductivity ratio,have a great impact on the mold flow subjected to an external magnetic field.     

Messverfahren zur Überprüfung randschichtnaher Veränderungen des Werkstoffzustandes als Folge mechanischer Oberflächenbehandlungen

Zur Charakterisierung der ermüdungsrelevanten Werkstoffveränderungen infolge hochfrequenter Schweißnahtnachbehandlung hat sich der Einsatz von mikromagnetischen Werkstoff‐ und Spannungsanalysen vorteilhaft gezeigt. Für Standardbauteile hat sich gezeigt, dass die Qualitätssicherung der Nachbehandlung mit höherfrequenten Hämmerverfahren bei Einhaltung der Behandlungsparameter durch eine Sichtkontrolle möglich ist. Das Mikromagnetische Verfahren ermöglicht bei neuen Anwendungsfällen eine Gütekontrolle der Nachbehandlung an Arbeitsproben ·und am Realbauteil. A measurement technique for inspection of material subsurface changes after mechanical surface treatment. The micro‐magnetic stress and material analysis has shown to be advantageous for characterizing the fatigue related material properties after high frequency post weld treatment. The quality control of standard parts treated by high frequency hammer peeing with the same peening parameters is possible by means of visual inspection. For new applications, the micro‐magnetic analysis provides a quality control of post weld treated work samples and real components.