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Energy management in distribution grids is one of the key challenges that needs to be overcome to increase the share of fluctuating renewable energies. Current control systems for energy management mainly demonstrate centralized- or decentralized-hierarchical control structures. Very few systems manifest a fully decentralized multiagent-based control structure. Multiagent-based control systems promise to be an advantageous approach for the future distributed energy supply system because no central control entity is necessary, which eases parameterization in case of grid topology changes, and the agents are more stable against failures and changes of control topologies. Research is necessary to prove these benefits. In this study, we introduce a design of a multiagent-based voltage control system for low-voltage grids. In detail we introduce cooperative decision-making processes and software solutions that allow the agents to perceive and control their environment, the agent-discovery and localization in different types of communication networks, agent-to-agent communication, and the integration of the multiagent system in existing grid-control infrastructures. Furthermore, the study proposes how different existing technologies can be combined into an applicable multiagent-based voltage control system: the Java/OSGi-based OpenMUC framework allows a generic field–device interaction; peer-to-peer discovery and session establishment functionalities are combined with the agent communication defined by the Foundation for Intelligent Physical Agents (FIPA). The ripple control-signal technology is applied as a fallback communication between the agent and a central grid-control center.
Turbinen aus der Tragetasche
(2014)
Am Karlsruher Institut für Technologie wurde der Prototyp eines Kleinwindkraftwerks zur autarken Stromversorgung entwickelt. Das "Energypack" genannte System besteht aus einem 1,10 m langen PVC-Gehäuse mit dreieckigem Querschnitt, Generator, Seilen sowie Funkgerät und kostet ab 50 Euro. Mit dem Energypack kann ein Dynamo mit 2,5 W angetrieben werden. An der Dualen Hochschule BW Heidenheim wurde das System "Anemotec" entworfen, das anstelle von Windflügeln über ein schraubenähnliches Gewinde verfügt. Der Rotor und die Windführung bestehen aus glasfaserverstärkten Werkstoffen. Die erzeugte Leistung liegt bei 365 W, die Stromgestehungskosten liegen bei 23 Cent pro kWh. Die von der Hochschule Offenburg entwickelte Windturbine "Windzip" arbeitet mit einem H-Rotor und besteht aus neun leicht gekrümmten Blechen, die wie Planeten in unterschiedlichem Abstand und in unterschiedlicher Höhe um einen vertikalen Stab kreisen. Bei einer Windgeschwindigkeit von 10 Meter pro Sekunde wurde damit eine Leistung von 40 W erzeugt.
Oft anfallende Prozesse und Aufgaben im IT-Umfeld kosten viel Zeit und personelle Ressourcen. Zudem können bei einer manuellen Ausführung dieser Aufgaben Fehler entstehen. Die Effizienz und die Wettbewerbsfähigkeit derer Unternehmen sinkt, die diese Aufgaben nicht unter Kontrolle haben. Ziel ist es wiederkehrende Aufgaben mit wenig Aufwand zu automatisieren und so das Fehlerpotential zu vermindern.
Eine besondere Herausforderung ergibt sich hierbei in der Aggregation der diversen verteilten Konten, wie Mitarbeiterlaptop, Server und online genutzte Dienste.
In dieser Arbeit sollen zunächst Anforderungen an die zu entwickelnde Lösung festgelegt werden. Die erarbeiteten Anforderungen sollen anschließend den vorhandenen Lösungen gegenübergestellt werden, um diese bewerten zu können. Anschließend erfolgt die Implementierung einer neuen oder Anpassung und Erweiterung einer vorhandenen Lösung.
Informationsvisualisierung im Kundenbeziehungsmanagement am Beispiel eines interaktiven Streamgraphs
(2014)
In dieser Arbeit wird der Streamgraph als Methode der Informationsvisualisierung im Kontext des Kundenbeziehungsmanagements vorgestellt. Neben der Auseinandersetzung mit den theoretischen Grundlagen dieser Themenbereiche wird die Eignung des Streamgraphs als Form der Visualisierung überprüft. Hierfür wird ein CRM-spezifischer Anwendungsfall erarbeitet und in einer webbasierten Applikation prototypisch realisiert. In diesem Zusammenhang werden Anforderungen in Bezug zu Interaktivität und Funktionalität aufgestellt und im Prototypen implementiert. Die Anforderungen an die Interaktivität orientieren sich hierbei an dem von Ben Shneiderman aufgestellten Mantra der visuellen Datenexploration.
In der abschließenden Auswertung wird eine bedingte Eignung für den Einsatz des Streamgraphs als effiziente Visualisierungsform im unternehmerischen Kontext festgestellt. Im Hinblick auf den Anwendungsfall erfüllt dieser zwar alle an ihn gestellten Anforderungen, die korrekte Lesbarkeit der Daten ist aufgrund seiner Form jedoch nicht gewährleistet.
A laser-operated, angle-tunable transducer was employed to excite selectively elastic waves guided along the apex of a solid wedge. The propagation of wedge waves at anisotropic monocrystalline silicon edges with different symmetry properties was studied by optical detection. The reduced symmetry in crystals, as compared to isotropic media, causes a number of new features, such as the existence of supersonic leaky wedge waves, tilted spatial pulse profiles, and other peculiarities of their localization. Experimental and theoretical results are presented for three different types of symmetry configurations: the wedge symmetric about its midplane, the wedge symmetric about the plane normal to its apex line, and the wedge symmetric about one of its faces. The experiments include accurate measurements of the phase velocity and the wave field distribution, providing information on localization and coupling of wedge waves with other waves. Theoretically, the wedge waves were treated by the Laguerre function method, extended to modes that are not localized at the tip of the wedge. This approach allowed an accurate description of the observed localized and leaky wedge waves in anisotropic wedges.
Hybrid SPECT/US
(2014)
This paper presents new measurements of a bronze cast from the right hand of the famous Italian violin virtuoso Nicolò Paganini (1782-1840). These are compared to anthropometric standard values. In addition, detailed dorsal and palmar views of the cast are shown. With a middle finger length of 75 mm, the palm width is 60 mm and the hand length 152 mm, which is significantly below the 5% percentile of today's standard values. Also the finger length index (0.55), the ratio of finger length to palm length (0.98) and the ratio of finger length to palm width (1.25) are significantly above normal limits. Hence, Paganini had abnormal hand measurements with a very small palm and relatively "long" fingers. This remarkable constellation, among others, could have been advantageous for his amazing skills as a violinist.
Monitoring of the molecular structure of lubricant oil using a FT-Raman spectrometer prototype
(2014)
The determination of the physical state of the lubricant materials in complex mechanical systems is highly critical from different points of view: operative, economical, environmental, etc. Furthermore, there are several parameters that a lubricant oil must meet for a proper performance inside a machine. The monitoring of these lubricants can represent a serious issue depending on the analytical approach applied. The molecular change of aging lubricant oils have been analyzed using an all-standard-components and self-designed FT-Raman spectrometer. This analytical tool allows the direct and clean study of the vibrational changes in the molecular structure of the oils without having direct contact with the samples and without extracting the sample from the machine in operation. The FT-Raman spectrometer prototype used in the analysis of the oil samples consist of a Michelson interferometer and a self-designed photon counter cooled down on a Peltier element arrangement. The light coupling has been accomplished by using a conventional 62.5/125μm multi-mode fiber coupler. The FT-Raman arrangement has been able to extract high resolution and frequency precise Raman spectra, comparable to those obtained with commercial FT-Raman systems, from the lubricant oil samples analyzed. The spectral information has helped to determine certain molecular changes in the initial phases of wearing of the oil samples. The proposed instrument prototype has no additional complex hardware components or costly software modules. The mechanical and thermal irregularities influencing the FT-Raman spectrometer have been removed mathematically by accurately evaluating the optical path difference of the Michelson interferometer. This has been achieved by producing an additional interference pattern signal with a λ= 632.8 nm helium-neon laser, which differs from the conventional zero-crossing sampling (also known as Connes advantage) commonly used by FT-devices. It enables the FT-Raman system to perform reliable and clean spectral measurements from the analyzed oil samples.
Packed beds serve as thermal energy storages (TES) and heat exchangers (HEX) in different technological applications. In this paper, a general heterogeneous model of heat transfer in packed beds is developed. It is implemented by lumped element formulation in object-oriented modeling language Modelica and is successful validated with data sets taken from two different experiments reported in literature.
The main advantages of the introduced model are the general, theory-based approach and the lumped element formulation in Modelica. The first point mentioned above should allow to simulate a packed bed TES/HEX without the necessity applying measured data for model calibration or to apply specific heat transfer correlations with restricted application. The second point establishes the possibility to integrate the TES/HEX model within plant models of larger scale without increasing the simulation time drastically.