Integrierte Informationsversorgung zur Entscheidungsunterstützung in Netzgesellschaften

Increasing regulatory requirements such as price cap regulation have increased the importance of strategic grid asset management. Empirical studies reveal that information supply and consolidation are error prone and long-term processes. The reason is the missing automation of extraction, transformation, and loading. The current gap does neither fulfill the requirements of regulatory nor the necessity of standardized reporting. Furthermore, a detailed planning is not enabled and the calculation of key figures is extensive. Currently, a framework that considers the coupling of financial and technical key figures, the coupling of strategic and operative key figures as well as the integration into information systems is not existent. Therefore, this paper addresses the design of a reference model as a recommendation for action to integrate the asset management within information systems. It is validated by expert interviews. Moreover, it provides information to integrate relevant financial and technical artifacts from distributed systems. Simultaneously it provides recommendations for implementing Business Intelligence in the context of strategic decision support.     

Model-based quality management of groundwater resources - catchment area Liedern, Germany

Strategies of groundwater protection in agricultural dominated areas are mainly based on a general reduction of the input of nutrients like nitrate. However, preventive measures in different parts of the catchment may provide very different effects on raw water quality. Exemplified on the case study 'Liedern' (BEW GmbH Bocholt, Germany) it is shown that hydrogeochemical processes along the flow path and in the well strongly affect the results of agricultural measures in terms of modality and efficiency. Thus, a reduction of fertilization in the vicinity of the well gallery leads to a decrease of nitrate concentration in the raw water. Whereas agricultural measures in the eastern part of the catchment do not influence nitrate, but cause a reduction of the iron concentration and rate of incrustation in the wells after 18 years. In this study we present a management tool that enables assessment of future trends in raw water quality. The tool is based on a reactive transport model which considers land use dynamics as an instrument to influence groundwater/raw water quality. A thermodynamic equilibrium approach is applied for modelling hydrogeochemical processes between aqueous, solid and gaseous phases. Kinetically controlled reactions like the microbial degradation of organic carbon are expressed by multiplicative Michaelis-Menten equations.     

Natural weathering performance and the effect of light stabilizers in water-based coating formulations on resin-modified and dye-stained beech-wood

This study assesses the performance of untreated and resin-modified beech-wood (Fagus sylvatica L.) during outdoor weathering. Boards modified with thermosetting N-methylol melamine (NMM) and phenol–formaldehyde (PF) resins, which were partly dye stained, were coated solely with a waterborne acrylic binder and formulations containing the same binder with different types and contents of photo-protective additives. Most modifications of the wood substrate changed the original color of wood, except for sole NMM modification. Changes in mass and capillary water uptake during exposure of modified, uncoated and coated boards were less than those of respective controls. Surface defects and cracks were clearly fewer on modified wood than on the controls, but no clear difference was observed among the topcoats containing UV-protective agents (UV-PA). The color stability during outside weathering depended on the treatment and coating formulation. Untreated and NMM-modified boards became grayer, and the NMM-dye-modified boards turned to a lighter gray, while PF-modified boards adopted a darker, blackish color. The weathered coating on the modified boards, particularly with PF resin, showed less blistering, flaking, and cracking than that on the controls. UV-PA stabilized the color and adhesion on all boards compared to the sole binder formulation. We conclude that wood modification with NMM and PF resin improves the natural weathering performance of wood coated with acrylic coatings. Combination of modification with staining enables diversification of the optical appearance.     

Optimierter mikrobiologischer Abbau von Chlorbenzen in In situ -Grundwasserreaktoren (SAFIRA)

In zwei Reaktoren der SAFIRA-Pilotanlage wurde der mikrobiologische Abbau von Chlorbenzen (CB) durch autoch-thone Bakterien in nativem Aquifersediment unter anoxischen und oxischen Bedingungen getestet. Unter anoxischen Bedingungen wurde CB nicht mikrobiologisch abgebaut. Die Zugabe von Wasserstoffperoxid (2,94 mM) und Nitrat (2 mM) in einem der beiden Reaktoren führte zum vollst?ndigen Abbau des zuflie?enden CB (0,2–0,3 mM) im unteren Teil des Reaktors, korrespondierend nahm die Anzahl aerober CB-metabolisierender Bakterien in diesem Reaktorbereich zu. Nach Reduzierung der Wasserstoffperoxidkonzentration auf 0,88 mM stiegen die CB-Konzentrationen im unteren Teil des Reaktors an, sanken aber, beginnend nach etwa 100 Tagen, wieder bis unter die Nachweisgrenze. Für den Abbau eines Mols CB wurden weniger als 4 Mol Sauerstoff ben?tigt. Im Reaktorwasser wurden keine sich anreichernden Verbindungen nachgewiesen, welche Hinweise auf einen unvollst?ndigen aeroben Abbau des CB geben k?nnten. Der aus H ₂ O ₂ bereitgestellte Sauerstoff ging nahezu vollst?ndig in den mikrobiologischen Abbau von CB ein. W?hrend der unterschiedlichen Versuchsphasen wurde das dosierte Nitrat im Reaktordurchlauf fast vollst?ndig verbraucht.     

The Nornir run-time system for parallel programs using Kahn process networks on multi-core machines—a flexible alternative to MapReduce

Even though shared-memory concurrency is a paradigm frequently used for developing parallel applications on small- and middle-sized machines, experience has shown that it is hard to use. This is largely caused by synchronization primitives which are low-level, inherently non-deterministic, and, consequently, non-intuitive to use. In this paper, we present the Nornir run-time system. Nornir is comparable to well-known frameworks such as MapReduce and Dryad that are recognized for their efficiency and simplicity. Unlike these frameworks, Nornir also supports process structures containing branches and cycles. Nornir is based on the formalism of Kahn process networks, which is a shared-nothing, message-passing model of concurrency. We deem this model a simple and deterministic alternative to shared-memory concurrency. Experiments with real and synthetic benchmarks on up to 8 CPUs show that performance in most cases scales almost linearly with the number of CPUs, when not limited by data dependencies. We also show that the modeling flexibility allows Nornir to outperform its MapReduce counterparts using well-known benchmarks.     

Colored Simultaneous Geometric Embeddings and?Universal Pointsets

Universal pointsets can be used for visualizing multiple relationships on the same set of objects or for visualizing dynamic graph processes. In simultaneous geometric embeddings, the same point in the plane is used to represent the same object as a way to preserve the viewer??s mental map. In colored simultaneous embeddings this restriction is relaxed, by allowing a given object to map to a subset of points in the plane. Specifically, consider a set of graphs on the same set of n vertices partitioned into k colors. Finding a corresponding set of k-colored points in the plane such that each vertex is mapped to a point of the same color so as to allow a straight-line plane drawing of each graph is the problem of colored simultaneous geometric embedding. For n-vertex paths, we show that there exist universal pointsets of size n, colored with two or three colors. We use this result to construct colored simultaneous geometric embeddings for a 2-colored tree together with any number of 2-colored paths, and more generally, a?2-colored outerplanar graph together with any number of 2-colored paths. For n-vertex trees, we construct small near-universal pointsets for 3-colored caterpillars of size n, 3-colored radius-2 stars of size n+3, and 2-colored spiders of size n. For n-vertex outerplanar graphs, we show that these same universal pointsets also suffice for 3-colored K ₃-caterpillars, 3-colored K ₃-stars, and 2-colored fans, respectively. We also present several negative results, showing that there exist a 2-colored planar graph and pseudo-forest, three 3-colored outerplanar graphs, four 4-colored pseudo-forests, three 5-colored pseudo-forests, five 5-colored paths, two 6-colored biconnected outerplanar graphs, three 6-colored cycles, four 6-colored paths, and three 9-colored paths that cannot be simultaneously embedded.     

Scheduled control for robust attenuation of non-stationary sinusoidal disturbances with measurable frequencies

Attenuation of sinusoidal disturbances with uncertain yet online measurable frequencies is considered. The disturbances are modeled as the outputs of an undisturbed parameter-dependent exogenous system with a skew-symmetric system matrix, obtained in response to nonzero initial conditions. The problem is formulated for a parameter-dependent plant as the synthesis of a parameter-dependent controller in a way to ensure internal stability as well as a desired level of steady-state disturbance attenuation in the face of all admissible parameter variations. The solvability of this problem is first related to the existence of bounded solutions to a matrix differential regulator equation subject to an asymptotic norm constraint. Reformulating this as a parameter-dependent state-feedback like synthesis, based on which suitable solutions to the differential regulator equation can be obtained online, tractable solvability conditions are then provided in the form of parameter-dependent matrix inequalities. Controllers that solve the generalized asymptotic regulation problem are also parameterized in terms of the suitable solutions of the differential regulator equation and some free parameter-dependent matrices that are to be designed off-line to ensure stability. A procedure is then developed to design the free parameters in a way to achieve desirable transient behavior. The use of the developed synthesis procedure is illustrated on a simplified version of the course control problem in ship steering.     

Proving Termination by Dependency Pairs and Inductive Theorem Proving

Current techniques and tools for automated termination analysis of term rewrite systems (TRSs) are already very powerful. However, they fail for algorithms whose termination is essentially due to an inductive argument. Therefore, we show how to couple the dependency pair method for termination of TRSs with inductive theorem proving. As confirmed by the implementation of our new approach in the tool AProVE, now TRS termination techniques are also successful on this important class of algorithms.     

Hate to interrupt you,but… analyzing turn-arounds from a cockpit perspective

This study aimed to analyze aircraft ground operation processes from a human factors perspective with special emphases on the occurrence and influence of interruptions on pilots’ workload. Interruptions have been shown to increase workload and error probability as well as to contribute to fatal accidents in various fields. Countermeasures have been initiated especially in high-risk environments such as those involving medical issues. In aviation, more explicitly during turn-around processes, interruptions might occur frequently and impair flight safety. One hundred and sixty fully certified pilots working for a European airline were observed during their turn-around while performing real operations. Pilots’ interruptions were documented and classified in order to predict subjectively perceived workload by use of multiple linear regression analysis. External factors such as weather conditions, technical problems, and time pressure were considered as covariates. On average, a pilot experienced about eight interruptions during a turn-around. Overall workload estimates showed a level comparable to that of manual flying in a simulator. Interruptions from colleagues or from outside the cockpit were found to predict pilots’ workload; however, further external factors such as poor weather conditions impacted workload even more strongly. We suggest two approaches based on our results to handling the high rate of interruptions. We first recommend procedural changes to diminish the interruption rate; second, we recommend comprehensive, line-oriented flight training for airline and ground staff to raise awareness about the negative influence of interruptions.