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Modern distributed engineering applications are based on complex systems consisting of various subsystems that are connected through the Internet. Communication and collaboration within an entire system requires reliable and efficient data exchange between the subsystems. Middleware developed within the web evolution during the past years provides reliable and efficient data exchange for web applications, which can be adopted for solving the data exchange problems in distributed engineering applications. This paper presents a generic approach for reliable and efficient data exchange between engineering devices using existing middleware known from web applications. Different existing middleware is examined with respect to the suitability in engineering applications. In this paper, a suitable middleware is shown and a prototype implementation simulating distributed wind farm control is presented and validated using several performance measurements.
Für die Ausführung des Oberbaus von Verkehrsflächen existiert in Abhängigkeit von projektspezifischen Voraussetzungen eine Vielzahl von verschiedenen Varianten. Aufgrund von Erfahrungen der Projektplaner werden bei ähnlichen Voraussetzungen häufig gleichartige Ausführungsvarianten gewählt. Um eine mögliche Lösungsvariante für den Straßenoberbau zu erhalten, sollten daher nicht nur die gesetzlichen Richtlinien sondern auch bereits beendete Projekte berücksichtigt werden. Im Rahmen eines Wissenschaftlichen Kollegs an der Bauhaus-Universität Weimar wurde die Anwendung des Case-Based Reasoning für die Auswahl von Ausführungsvarianten für den Straßenoberbau untersucht. In diesem Beitrag werden die grundlegenden Konzepte des Case-Based Reasoning und die Bestimmung von ähnlichen Varianten anhand einfacher Beispiele aus dem Straßenoberbau dargestellt.
Geotechnical constructions are sophisticated structures due to the non-linear soil behaviour and the complex soil-structure interaction, which entails great exigencies on the liable engineer during the design process. The process can be schematised as a difficult and, depending on the opportunities and skills of the processor more or less innovative, creative and heuristic search for one or a multiple of defined objectives under given boundary conditions. Wholistic approaches including numerical optimisation which support the constructing engineer in this task do not currently exist. Abstract problem formulation is not state of the art; commonly parameter studies are bounded by computational effort. Thereby potential regarding cost effectiveness, construction time, load capacity and/or serviceability are often used insufficiently. This paper describes systematic approaches for comprehensive optimisation of selected geotechnical constructions like combined pile raft foundations and quay wall structures. Several optimisation paradigms like the mono- and the multi-objective optimisation are demonstrated and their use for a more efficient design concerning various intentions is shown in example. The optimisation is implemented by using Evolutionary Algorithms. The applicability to geotechnical real world problems including nonlinearities, discontinuities and multi-modalities is shown. The routines are adapted to common problems and coupled with conventional analysis procedures as well as with numerical calculation software based on the finite element method. Numerical optimisation of geotechnical design using efficient algorithms is able to deliver highly effective solutions after investing more effort into the parameterization of the problem. Obtained results can be used for realizing different constructions near the stability limit, visualizing the sensitivity regarding the construction parameters or simply procuring more effective solutions.
The quaternionic operator calculus can be applied very elegantly to solve many important boundary value problems arising in fluid dynamics and electrodynamics in an analytic way. In order to set up fully explicit solutions. In order to apply the quaternionic operator calculus to solve these types of boundary value problems fully explicitly, one has to evaluate two types of integral operators: the Teodorescu operator and the quaternionic Bergman projector. While the integral kernel of the Teodorescu transform is universal for all domains, the kernel function of the Bergman projector, called the Bergman kernel, depends on the geometry of the domain. Recently the theory of quaternionic holomorphic multiperiodic functions and automorphic forms provided new impulses to set up explicit representation formulas for large classes of hyperbolic polyhedron type domains. These include block shaped domains, wedge shaped domains (with or without additional rectangular restrictions) and circular symmetric finite and infinite cylinders as particular subcases. In this talk we want to give an overview over the recent developments in this direction.
Grundidee der Arbeit ist es, Lösungen von Randwertaufgaben durch Linearkombinationen exakter klassischer Lösungen der Differentialgleichung zu approximieren. Die freien Koeffizienten werden dabei durch die Bestimmung der besten Approximation der Randwerte berechnet. Als Basis der Approximation werden vollständige orthogonale und nahezu orthogonale Funktionensysteme verwendet. Anhand ausgewählter Beispiele mit Randvorgaben unterschiedlicher Glattheit wird am Beispiel der Kugel die prinzipielle Anwendbarkeit der Methode getestet und hinsichtlich der Entwicklung des Fehlers der Näherungslösung, der Stabilität des Verfahrens und des numerischen Aufwandes untersucht. Die erhaltenen Resultate geben einen begründeten Anlass, die Anwendung der Methode als Bestandteil einer hybriden analytisch-numerischen Methode, insbesondere der Verknüpfung mit der FEM, weiterzuverfolgen.
Prozesse im Bauingenieurwesen sind komplex und beinhalten eine große Anzahl verschiedener Aufgaben mit vielen logischen Abhängigkeiten. Basierend auf diesen projektspezifischen Abhängigkeiten wird gewöhnlich ein Bauablaufplan manuell erstellt. In der Regel existieren mehrere Varianten und somit alternative Bauabläufe um ein Projekt zu realisieren. Welche dieser Ausführungsvarianten zur praktischen Anwendung kommt, wird durch den jeweiligen Projektmanager bestimmt. Falls Ä;nderungen oder Störungen während des Bauablaufs auftreten, müssen die davon betroffenen Aufgaben und Abläufe per Hand modifiziert und alternative Aufgaben sowie Abläufe stattdessen ausgeführt werden. Diese Vorgehensweise ist oft sehr aufwändig und teuer. Aktuelle Forschungsansätze beschäftigen sich mit der automatischen Generierung von Bauabläufen. Grundlage sind dabei Aufgaben mit ihren erforderlichen Voraussetzungen und erzeugten Ergebnissen. Im Rahmen dieses Beitrags wird eine Methodik vorgestellt, um Bauabläufe mit Ausführungsvarianten in Form von Workflow-Netzen zu jeder Zeit berechnen zu können. Die vorgestellte Methode wird anhand eines Beispiels aus dem Straßenbau schematisch dargestellt.
In order to minimize the probability of foundation failure resulting from cyclic action on structures, researchers have developed various constitutive models to simulate the foundation response and soil interaction as a result of these complex cyclic loads. The efficiency and effectiveness of these model is majorly influenced by the cyclic constitutive parameters. Although a lot of research is being carried out on these relatively new models, little or no details exist in literature about the model based identification of the cyclic constitutive parameters. This could be attributed to the difficulties and complexities of the inverse modeling of such complex phenomena. A variety of optimization strategies are available for the solution of the sum of least-squares problems as usually done in the field of model calibration. However for the back analysis (calibration) of the soil response to oscillatory load functions, this paper gives insight into the model calibration challenges and also puts forward a method for the inverse modeling of cyclic loaded foundation response such that high quality solutions are obtained with minimum computational effort. Therefore model responses are produced which adequately describes what would otherwise be experienced in the laboratory or field.
Rapid advancements of modern technologies put high demands on mathematical modelling of engineering systems. Typically, systems are no longer “simple” objects, but rather coupled systems involving multiphysics phenomena, the modelling of which involves coupling of models that describe different phenomena. After constructing a mathematical model, it is essential to analyse the correctness of the coupled models and to detect modelling errors compromising the final modelling result. Broadly, there are two classes of modelling errors: (a) errors related to abstract modelling, eg, conceptual errors concerning the coherence of a model as a whole and (b) errors related to concrete modelling or instance modelling, eg, questions of approximation quality and implementation. Instance modelling errors, on the one hand, are relatively well understood. Abstract modelling errors, on the other, are not appropriately addressed by modern modelling methodologies. The aim of this paper is to initiate a discussion on abstract approaches and their usability for mathematical modelling of engineering systems with the goal of making it possible to catch conceptual modelling errors early and automatically by computer assistant tools. To that end, we argue that it is necessary to identify and employ suitable mathematical abstractions to capture an accurate conceptual description of the process of modelling engineering systems.
In this paper we present a theoretical background for a coupled analytical–numerical approach to model a crack propagation process in two-dimensional bounded domains. The goal of the coupled analytical–numerical approach is to obtain the correct solution behaviour near the crack tip by help of the analytical solution constructed by using tools of complex function theory and couple it continuously with the finite element solution in the region far from the singularity. In this way, crack propagation could be modelled without using remeshing. Possible directions of crack growth can be calculated through the minimization of the total energy composed of the potential energy and the dissipated energy based on the energy release rate. Within this setting, an analytical solution of a mixed boundary value problem based on complex analysis and conformal mapping techniques is presented in a circular region containing an arbitrary crack path. More precisely, the linear elastic problem is transformed into a Riemann–Hilbert problem in the unit disk for holomorphic functions. Utilising advantages of the analytical solution in the region near the crack tip, the total energy could be evaluated within short computation times for various crack kink angles and lengths leading to a potentially efficient way of computing the minimization procedure. To this end, the paper presents a general strategy of the new coupled approach for crack propagation modelling. Additionally, we also discuss obstacles in the way of practical realisation of this strategy.
Sensor faults can affect the dependability and the accuracy of structural health monitoring (SHM) systems. Recent studies demonstrate that artificial neural networks can be used to detect sensor faults. In this paper, decentralized artificial neural networks (ANNs) are applied for autonomous sensor fault detection. On each sensor node of a wireless SHM system, an ANN is implemented to measure and to process structural response data. Structural response data is predicted by each sensor node based on correlations between adjacent sensor nodes and on redundancies inherent in the SHM system. Evaluating the deviations (or residuals) between measured and predicted data, sensor faults are autonomously detected by the wireless sensor nodes in a fully decentralized manner. A prototype SHM system implemented in this study, which is capable of decentralized autonomous sensor fault detection, is validated in laboratory experiments through simulated sensor faults. Several topologies and modes of operation of the embedded ANNs are investigated with respect to the dependability and the accuracy of the fault detection approach. In conclusion, the prototype SHM system is able to accurately detect sensor faults, demonstrating that neural networks, processing decentralized structural response data, facilitate autonomous fault detection, thus increasing the dependability and the accuracy of structural health monitoring systems.